Mountain Dulcimer Strings
General mountain dulcimer or music discussions
Welcome to the forum, and the world of dulcimers, Garland. I personally use .024, .016, and .012. on my Gallier A-frame. I have tried several different sizes and combinations, but keep coming back to these 3 sizes for my A-frame. I think my McSpadden has the same sizes as yours.
By the way, if you get tired of the scratching noise when you slide your finger on the wrapped base string (you'll really notice it on recordings), I find that the Elixir brand wrapped strings are virtually silent. They are micro-coated with something to fill in the cracks between the wraps, and also make the string slicker. They cost a little more but they last a good deal longer than the common brands as well.
Dewey

I suggest you just start in CGG and learn to play a simple song like Hot cross Buns or Frere Jacques, rather than trying to transpose guitar or uke music right off the bat. You need to understand the very most basic simple concepts of tuning and playing the dulcimer, without worrying about what you do on other instruments ...for now.