Walkthrough for the "Tribes of the East" expansion.

Hey everyone. I recently got into Heroes 5, and I really like the game. I have a question. Right now, I'm stuck in the Orc campaign, mission 3. I've taken down some towns, but I haven't really managed to develop the infrastructure of the towns. I'm wandering around the map and can't figure out what to do. Should I be picking up random stuff, grabbing mines, or fighting people? I also can't seem to build up my army. Can you give me some tips on how to complete this mission? By the way, the red player has a pretty strong army. I have a feeling I'm in trouble. Help me, please!