i have the key code but no clue how to enter it..email did not help.

If you purchased Fish Tycoon for Windows from the LDW site, you can find instructions and screen shots of the registration process in the thread "How to enter key in Fish Tycoon for Windows" (currently the third thread from the top).

If you purchased the game from another site, since their registration codes are different, you should check that site's support page for assistance with entering the registration code.