Hmm, this isn't bad for your first song (mime was complete trash)! I like the tone you got going there, it sounds like the intro to a cool boss theme. Some advice I can give is to learn a bit of music theory. That will not only make your songs sound better, but will also help you create new ones! Don't be afraid to experiment. Another piece of advice is to listen to favorite Famitracker songs (I suggest the ones in the demo folder). See what makes them so good, such as what effects they use and what they do to the instruments. Famitracker is a tough program to get the hang of, but you'll get there, just keep trying to improve!
I hope this helps, and if you have any questions, feel free to message me!(I'll try to make an edit of your song later)