It took me a while to learn too xyleanne. It gets to be a lot of fun once it stops looking like Greek. You learn which guys go first, which of your guys are best against which of their guys. Then you start winning! After you have learned a bunch you go back and watch the stupid AI make terrible decisions and cost you all kinds of fighters!!
Let me see if I can give you some basic tips:
Each type of province (gems, planks, crystal, etc.) have their own kinds of fighters. So after a while you just know that some types of fighters will be good for some types of provinces. For example....the crystal province. I learned those first...they are my favorite! Take the most advanced treants you have and just hit them silly! You will be up against green orcs and the red doggies. When I hit the doggies, I say "bad doggie" in my head and it is fun! Try to surround the enemy the best you can. You want all the treants hitting them when they get a turn. If you see that one of your treants might kill an enemy the next round, you don't need all your other treants in line to hit the same bad guy. (Since he will already be dead the first time you hit him)
Another easy province, are the ones with archers and cannoneers IF you have sorceresses. Because once a sorceress hits one of those types of enemies, they can't hit you back! Oh, they try, but they hit back and do zero damage!!
Try just those two kinds and get a feel for how your guys move, and how they move. It should help! In the beginning though, I would sit and watch the AI battle. At least that gives you an idea of how things move.
That is the hardest part!