I play mountain, and I've belonged to a club as well. To play this instrument, you have to learn to sound pieces out. You also have to know a lot of tunes in the first place. After that, it's duck soup.

I usually play in D-A-A, with D being the low string. In this tuning, if you play the A string (closest to you) with your index finger and put your 4th finger on the D srring one fret behind the inxdex finger, you have a chord. Two exceptions - for the note A, put the 4th finger on the 5th fret, and for B, put it on the 6th fret. Next, think of a major tune and start strumming. If you play guitar, this should come easily.

I don't think there is any instrument that is as easy to play a melody plus harmony as the mountain dulcimer.

I don't double the melody string, because it's too hard to tune the two of them perfectly. I use a soft thumb pick to bring out the melody instead.