How to add ERC1155 to this Smart Contract

so I have two smart contracts and I want to add erc1155 functionalities this is the first one:

1; name: NFT.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";
import "@openzeppelin/contracts/utils/Counters.sol";


contract NFT is ERC721URIStorage {
    using Counters for Counters.Counter;
    Counters.Counter private _tokenIds;
    address contractAddress;

constructor(address _marketplaceAddress) ERC721("Metaverse Tokens", "METT") {
    contractAddress = _marketplaceAddress;
}

function createToken(string memory _tokenURI) public returns (uint) {
    _tokenIds.increment();
    uint256 newItemId = _tokenIds.current();

    _mint(msg.sender, newItemId);
    _setTokenURI(newItemId, _tokenURI);
    setApprovalForAll(contractAddress, true);
    return newItemId;
}

}

and the sencond:

2; named: NFTMarket.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import "@openzeppelin/contracts/utils/Counters.sol";

contract NFTMarket is ReentrancyGuard {
    using Counters for Counters.Counter;
    Counters.Counter private _itemIds;
    Counters.Counter private _itemsSold;

    address payable owner;
    uint256 listingPrice = 0.025 ether;

    constructor() {
        owner = payable(msg.sender);
    }

    struct MarketItem {
        uint itemId;
        address nftContract;
        uint256 tokenId;
        address payable seller;
        address payable owner;
        uint256 price;
        bool sold;
    }

    mapping(uint256 => MarketItem) private idToMarketItem;

    event MarketItemCreated (
        uint indexed itemId,
        address indexed nftContract,
        uint indexed tokenId,
        address seller,
        address owner,
        uint256 price,
        bool sold
    );

    function getListingPrice() public view returns (uint256) {
        return listingPrice;
    }

    function createMarketItem(address _nftContract, uint256 _tokenId, uint256 _price) public payable nonReentrant {
        require(_price> 0,"Price must be at least 1 wei");
        require(msg.value == listingPrice, "Price must be equal to listiing price");

        _itemIds.increment();
        uint256 itemId = _itemIds.current();

        idToMarketItem[itemId] = MarketItem(
            itemId,
            _nftContract,
            _tokenId,
            payable(msg.sender),
            payable(address(0)),
            _price,
            false
        );
        IERC721(_nftContract).transferFrom(msg.sender, address(this), _tokenId);

        emit MarketItemCreated(itemId, _nftContract, _tokenId, msg.sender, address(0), _price, false);
    }

    function createMarketSale(address _nftContract, uint256 itemId) public payable nonReentrant {
        uint price = idToMarketItem[itemId].price;
        uint tokenId = idToMarketItem[itemId].tokenId;
        require(msg.value == price, "Please submit the asking price in order to complete the purchase");

        idToMarketItem[itemId].seller.transfer(msg.value);
        IERC721(_nftContract).transferFrom(address(this), msg.sender, tokenId);
        idToMarketItem[itemId].owner = payable(msg.sender);
        idToMarketItem[itemId].sold = true;
        _itemsSold.increment();
        payable(owner).transfer(listingPrice);
    }

    function fetchMarketItems() public view returns (MarketItem[] memory) {
        uint itemCount = _itemIds.current();
        uint unsoldItemCount = _itemIds.current() - _itemsSold.current(); 
        uint currentIndex = 0;

        MarketItem[] memory items = new MarketItem[](unsoldItemCount);
        for (uint i = 0; i < itemCount; i++) {
            if (idToMarketItem[i+1].owner == address(0)) {
                uint currentId = idToMarketItem[i + 1].itemId;
                MarketItem storage currentItem = idToMarketItem[currentId];
                items[currentIndex] = currentItem;
                currentIndex +=1;
            }
        }
        return items;
    }

    function fetchMyNFTs() public view returns (MarketItem[] memory) {
        uint totalItemCount = _itemIds.current();
        uint itemCount = 0;
        uint currentIndex = 0;

    for (uint256 i = 0; i < totalItemCount; i++) {
        if(idToMarketItem[i+1].owner == msg.sender) {
            itemCount+=1;
        }
    }

    MarketItem[] memory items = new MarketItem[](itemCount);
    for (uint256 i = 0; i < totalItemCount; i++) {
        if(idToMarketItem[i +1].owner == msg.sender) {
            uint currentId = idToMarketItem[i +1].itemId;
            MarketItem storage currentItem = idToMarketItem[currentId];
            items[currentIndex] = currentItem;
            currentIndex += 1;
        }
    }
    return items;

    }

    function fetchItemsCreated() public view returns (MarketItem[] memory) {
         uint totalItemCount = _itemIds.current();
        uint itemCount = 0;
        uint currentIndex = 0;

    for (uint256 i = 0; i < totalItemCount; i++) {
        if(idToMarketItem[i+1].seller == msg.sender) {
            itemCount+=1;
        }
    }

    MarketItem[] memory items = new MarketItem[](itemCount);
    for (uint256 i = 0; i < totalItemCount; i++) {
        if(idToMarketItem[i +1].seller == msg.sender) {
            uint currentId = idToMarketItem[i +1].itemId;
            MarketItem storage currentItem = idToMarketItem[currentId];
            items[currentIndex] = currentItem;
            currentIndex += 1;
        }
    }
    return items;

    }

}

The aim is to support both ERC721 and ERC1155 on the marketplace

Please elaborate a little more.

Did you attempt to add ERC1155? What failed?