It is my understanding that by simply extending the ERC20Burnable contract, you can call Burnable methods such as burn() and burnFrom() directly through an instance of your contract. No need to expose them again in your contract unless you are specifically overriding some parent functionality of the contract.
Open Zeppelin contracts can be extended and used as is.
Just like i said, I am new to Solidity and zepellin. If I were to use it the way we do use it in PHP ( which I am largely familiar with ), I did just do something like this
Take a look at Contracts Wizard to see how to include burn functionality in your token:
As for how to invoke this functionality, that depends on whether you want to invoke it from "outside" the blockchain e.g. from a web app, or from "inside" the blockchain i.e. from another Solidity smart contract.
I am happy I got your attention. Actually, it was in one of your suggestions to another newbie then about the newbie going through the solidity doc and solidity examples that got my interest about learning it from scratch instead of just the copy-paste I have been using for quite a while now.