Starting simple

The real beauty of noter & drone style playing is its simplicity. If you can hum Mary Had a Little Lamb, then you can play it on your melody string with no need for a tab arrangement to guide you.
Chords have made things complicated enough for people to feel they need tab to get all the fingerings. There ARE no 'fingerings' in noter, fingerdancing, or Galax style playing... You play the simple melody line on the melody string, and the open drone strings will provide additional interval notes that will sound full, and you won't need to refer to 'fingering positions'. Many folks grow to love the sound of the mode intervals changing against the open unchanging drones.

Start SIMPLY, with a very simple melody you know. You will get better steadily if you just play easy stuff and have fun with trying to pick out melodies. Save the tricky tunes til later. Every time you get frustrated just go back a step to something easier. Once you can play Go Tell Aunt Rhody or Mary Had a little lamb without having to concentrate too hard, then move on to Twinkle Little star or Three Blind Mice or Frere Jacques. To start, perhaps you could tune your dulcimer (from bass side to melody string side) D-A-AA. This is tuning in the Ionian mode. Your key note of D in your melody will start on your THIRD fret on your melody string that is tuned to A. Your third fret will be a D, and you'll be playing in the key of D. Start playing Twinkle Twinkle Little Star on your melody string(s) starting and ending on your third fret. You will be playing in Ionian mode.

Good rhythm comes with practice and time. Rhythm is just as important as notes. Don't even worry or think about speed- speed just comes automatically as the months go by. Speed should not be a goal.
Try a longer more flexible pick. Try cutting a pick out of a stiff plastic take-out container from a Deli- make it 1 1/2" long and about a 1/2" wide, tapering to a rounded end. As you get faster, you might not want stiff short Herdim picks for playing fast tunes. Don't do any flatpicking on various strings. Basically you are strumming across all strings every time. Personally, I never flatpick at all- and flatpicking is a technique that is already amply covered in the teachings of more modern dulcimer playing styles. Some people do, however, angle their pick sometimes so they they purposely avoid hitting the drones on certain parts of the tune. Or, they angle it to only hit a low drone on some particular beat. These are cool techniques you can experiment with later.

Your beginning rhythm strum will be something like DOWN, down-up, DOWN, down-up. Like a galloping horse sound. Go to my YouTube Channel, HERE, and watch my videos about beginning strumming and using a noter.
Work on the strums and then work in your notes like TWINK, kel-l, TWINK, kel-l, LIT, tel-l, STAR, down-up.... You may need to practice your strum rhythm by holding your left hand on the strings to mute them and just practice your strumming without driving everyone in the neighborhood insane. Nothing comes without practice, but just remember that the first few days are the very hardest, from then on it will slowly, slowly get EASIER. Don't be frustrated, just try to enjoy the simple zen quality of the resonant sounds you are making. Think of yourself as a loon calling out a single lonesome note that echoes over the lake. There is profound beauty in a single heartfelt note. Let it come from within you and enjoy its pure beauty.