How do i do this? it says its encoded with base58 and when i copy paste the entire text of the multibit.key it says error decrpyting wallet
What am i doing wrong, do i need to decode the base58 private key?
if so how do i do it, please keep this simple i'm bad at technical stuff..
Why don't you just upload the .key file to blockchain directly?
I believe blockchain.info can only read wallet.dat (bitcoin-qt) and wallet.aes.json directly.
From:
https://blockchain.info/wallet/features 
Import / Export
Multiple Private Key Formats - Mini private keys, Wallet Import Format, Base58, Base64 and Hex.
Watch Only - Watch Only addresses allow you to view transactions at an address without storing the private key in your wallet.
Brain Wallet - Generate A private key from a passphrase.
Import From QR Code - Scan A private key using a webcam.
Import Wallet Files - Vanitygen, pywallet, blockchain.info and multibit .key files supported.Export Encrypted or Unencrypted.
JSON RPC Import - Import / Export using the bitcoind JSON RPC API
Paper Wallets
Sign Message - Sign a message to prove you own a bitcoin adddress.
Verify Message - Verify the owner of a bitcoin address.
Import Bitcoin-Qt Wallet - Import keys from a wallet.dat file.
Thanks for that. Looks like you are right.
) long long time before, and it only handles the 2 wallets I mentioned.
BTW, they forget to mention bitcoin-qt in the features page.