I have been offered a farm for free. I have the email and password with it's location how do I access..

Make sure your current game is successfully bound to a separate IM30 account so that you don't lose it. Then go to the settings menu and select the account option. Choose the 'Switch account' option here and then the type of account you are logging in to. (presumably an IM30 account) Next find the 'Add account' button and enter the log in details. This will let you load the other game. It will overwrite the game you are playing on your device. But you can then switch back to your original game at any time as long as it is bound to a different IM30 account.