Alfonsocsr,
Professional Soldiers and Officers, can only be obtained using Gold Coins.
To Purchase Professional military staff.
1) Click the "Direct Trading" tab. This should be a button on the left hand side of your screen.
2) You should now be on the "Direct Trading" page. There should be a list with the heading "Buy or Sell Products using Gold Coins". On that list there are products, including Professional Soldiers and Officers.
3) Click the "Trade" button, that corresponds to the item you wish to purchase. These buttons should be on the right hand side of the list.
4) This will take you to a list of Buy/Sell orders for the product you wish to buy.
Signed President of DanNation on LU