There are four basic orders you can give a unit:
The “Hold” order has the unit stay in place for the turn. Units that receive no orders automatically default to a hold order.
The move order allows the unit to move one space to a viable target province. If contact is made with the enemy, we’ll refer to this as an attack, but the order is simply “move”
With a support order, your unit lends it’s combat powers to another. In this case, one army supports the hold order of the other. You must specify the type of order you are supporting and that order’s target.
In this case one army is supporting the move order of another. The support order needs to specify who is being supported, what kind of action the supported unit is taking, and to where. (ex: Army Silesia supports Army Bulgaria’s move to Rumania)
The support order is by far the most complex. Here is more information on giving support and cutting it.
Fleets can transport armies across the water with a “convoy” order.
Convoy rules are explained in depth here.
Examples of written orders
Army bul moves to ser
Army con supports army bul
Fleet bla supports army bul move to rum / army bul moves to rum