Play it however you want, but do record.
Not intending anything other than an easy discussion on the various ways to approach learning a new instrument.
1. Get a book or dvd
2. Read info here
4. Do a little of number 3, but really just start to play the instrument. Very soon you will know if using a noter is comfortable for you, or using just your fingers. Do what feels and sounds good to you. If you need to know what Mixlodian means - then look it up. If you don't care about any of the technical stuff at all then don't worry about it. If you want to learn music theory - again it's all here, or if you just want to play and not think about all that - that is perfectly fine too.
Basically I just want folks to understand that this can be as simple or as difficult as you would like it to be. You can learn to play without ever reading the first thing by experimenting and playing by ear. Or you can get books, videos, and dive deep into the pool of learning everything there is to know about the dulcimer.
It's wonderful how many options are out there for folks to read about. But I do want you to know that you can just play the thing too without worrying or "fretting" over it.
My personal choice of the above is to do #4. I read a bit and if I am interested I keep on reading, if not I go play. I watch videos of people playing and maybe pick up a lick or something that I haven't seen or done and want to try out. But mostly I don't worry about much of anything and just play for fun. Though I may practice a particular piece 100 times trying to embellish it, it's still fun.
One learning tool I like to use is to record myself playing. Either video or audio. This is a great tool to really hear what you are doing. Does it sound good? Does it sound like the song? Does it flow or get bogged down in sections and get muddy? Doesn't matter if you share it here or not, you will be able to hear these things if you listen to them. Plus you can go back 6 months from now and you will be amazed at how far you've progressed. If you listen after the 6 month mark and don't hear improvement, maybe it's time to revisit your technique, rhythm, strumming, noting or whatever you are doing.