On which site can you legally download Forest Gump movies and music for free?
There are no sites on which you can legally download Forest Gump movies or music for free. That is a copyrighted movie for which payment is expected. Downloading it free is a violation of the copyright laws and is the same as leaving a store without paying for a DVD.
Finding a site where you can download the movie legally by paying for it or buying the DVD from a store is the only way you can legally own a copy of it.