How do I lookup data in one form and populate it in another

How do I lookup data in one form and populate it in another

I have two forms - one a registered players form that I will be pre-populating with an import file. I have a registration page where I want a volunteer to put in the last name of a player and if there is a match populate the registration page with all the information we have on that player - I have tried the fetch records but cannot get past an error message - any scripting help would be very much appreciated