Many people don't understand the difference between producing and DJing. Simply said, a DJ is an entertainer who plays pre-recorded music for crowds. Also simply said, a Producer is someone who makes or remakes (aka remixes) music in a studio. In any case, when on DJF, look for DJs to post mixes and such and look for Producers to post their own created tracks and/or remixes of other tracks.
Obviously, there are DJs who are Producers and Producers who are DJs. Blurring the line further, there is a movement called Live Remixing that does just that. DJ Enferno is the poster-child for this type of performance.
DJs typically use decks to make music and work with entire tracks. If software is used, the software usually emulate decks for digital audio playback using MP3s - like DJ apps and DVS software. At the end, a DJ performs a mix that is comprised of a sequence of songs.
Producers work with elements of tracks and add/remove those elements to remix the track into something that didn't exist before. In this way, they work as computer-aided composers who sometimes just "spice up" the beat or create whole new music passages. They use Digital Audio Workstation software, Digital Audio Editors, and many (sooo many) plugins to make their magic happen. At the end, they have a newly made track that can be used by a DJ in a DJ Mix.