http://en.wikipedia.org/wiki/First_Bull_Run_Union_order_of_battleThis is what you have, if you're interested. Generally all you need to know is the overall number, and figure out a strategy for yourself.
Right now, consider your troops encamped in Washington. The rebels are somewhere in northern Virginia. Your first task would be seeking them out and finding them. Both your army and the Confederates is fairly untrained. But you outnumber them.
*check the first post for rules and additions to the rules etc, if you have any questions feel free to ask.
Advice:
Stick near railroads and roads if you can, going outside these will cost more supply. Try not to attack an army across a river. Send out scouts in the directions you expect the enemy, if you can locate them and their marching direction or what theyre doing, you may have the upper hand in attacking or avoiding.
I will be using nearly entirely text to resolve and plan the battles, so you WILL need to look at the map for reference as to whats happening where.
You can detach your corps and division commanders to do other tasks, such as patrol a flank or scout in force. Always wiki the leaders currently at your disposal though, so you can pick a decent one. As he will be independantly in command of troops. and try not to fight a major battle with only part of your troops.