Aieee, help!

I apparently forgot (blocked out?) how hard trying to jump into the middle of choir practice can be, especially for a non-site-reading dork like me.  Yeah, they were happy to have me, another Tenor, to sing with the choir.  That's the good part.  The bad part is of the 3 songs we practiced, I can only really sing one of them correctly.  Yeah.  Doomed.  Help.