In a previous post I covered the concept of setting up a new site and warehouse. Adjusting inventory can be done with journals like the movement and inventory adjustment journal. If you need to move inventory between warehouses you can use the transfer journal. Typically this would be used for an adjustment, if you are looking for a document process to do shipping and receiving for transfers between warehouses then look to the transfer order. This walk through will give you an overview of the transfer journal
This video was recorded with AX2012 R2 but the same concepts apply to any release of AX2012.