Hey Courtney, welcome to the forum.
Just surf through the forum and you will find all the info.
The two important requesters who put the transcription jobs are CastigWords and Speechink. You can find a lot of details about these requesters in this forum. There is a dedicated sub-forum for CastingWords in the section 'Requesters'
Beware of the shady requesters, use turkopticon, turkalert...