You need to update your wallet to the latest version before block 4,370,000 or it will be stuck on the old chain and unable to broadcast transactions after the fork. Pools should have already updated, so as miner on a pool there is nothing else you need to do. For solo mining you would need to update to the latest version of Geth.
https://blog.ethereum.org/2017/10/12/byzantium-hf-announcement/My wallet was created through myetherwallet.com in december last year. I hold some ether in that wallet. Do I need to change anything?