Katlaughing,

If you look at the tuning for a mandolin, it is an inversion of the lowest four strings of a guitar. Therefore, you can invert any guitar chord and get the same chord on the mandolin. Of course, mandolin players eventually found some easier ways to do some chords, but for starters, that will carry you through many a song.

Roger in Baltimore (who stopped playing mandolin when his four year old son sat on Roger's $10 hock shop special)