Let’s see if I can explain better 
When Alice wants to send some 
to Bob, she enters Bob’s wallet address, the amount, a fee and clicks Send.
Now the “transaction” is put in the mempool, aka a queue for all the transactions before they are validated and added to a block in the blockchain.
Joe, the lucky farmer, founds a proof and win the block that includes Alice’s transaction. Joe earns the 2 XCH reward from the network as well as all the transactions fees (there can be multiple transactions in a block, I don’t know the maximum number though 
). So Joe gets the fee that Alice paid when she made her transaction.
In reality, it’s slightly more complex as more than 1 farmer can win a block, so I assume the fees gets split across all winners.