Sure, here are four ways to play an Aadd9 chord (check out the attached image). The last one is probably the easiest one, essentially an A barre chord but with the B string and the high E string open.

The "add9" means that you should add the note B to the regular A major triad. An A major triad consists of the notes A, C#, and E. Aadd9 consists of A, C#, E, and B.