Here's the first song using the A string so far — it's called Blow the Man Down; apparently, it was an English shanty (which were call-and-response songs, led by a "shantyman") sung at sea.
You'll only use the 3rd, 4th, and 5th strings for this song, but here are all the notes you've learned thus far for your review.
Keep in mind that this song is played in 3/4 time, which is a waltz; here's a segment on Time Signatures in case you feel like reviewing.
Good luck working through this one. Another one is coming up.