Importing a PO can be done by clicking the three-dot menu on the upper-right corner of the page. Meanwhile, you can create a PO as simple as how you create a sale -- search for the items you need in the search bar or scan a barcode.
A PO# will be suspended when you have accomplished filling out a Purchase Order you will send to your distributor/manufacturer. You will unsuspend it every time you receive an item to keep track of the items that are still subject to delivery. When all of the items in the PO are already received, you can finalize and close it.
You can suspend a PO by clicking the "Suspend" button (pointed by the red arrow) once the items you want to order are already listed on the screen.
You can receive against the existing/pending POs you have by looking that PO# up on the box pointed by the green arrow.
When looking up a PO#, you should then click "Get Items" so that the contents of that PO# you suspended will be brought to the screen. You can then continue filling up the PO whenever necessary.
Lastly, whenever the PO has already been fulfilled, you can check the box beside "Mark Complete," signifying that the transaction for that PO has already been completed.
You can read more about receiving against PO's by clicking here.