A professional shop will use nitrogen to pressurize the system and check for leaks. But before that step, check to see if your AC system already has (had) leak dye in it. All the systems come that way from the factory (that I've seen) have leak detector dye in them. However, you may need to purchase a black light to see the fluorescent dye (depending on what type of dye was used originally). Your owner's manual should say what was put in with the factory charge.
Once the leak is repaired, you would need to change the Dryer. It is only designed to remove a little moisture in a closed system. once the Dryer is open to atmosphere it will become saturated and needs to be replaced.
The difficultly in this type of repair (fixing a leak and recharging) is that you cant tell how much oil came out with the leak.
If you recharge and add too much oil the system wont cool properly. If you don't add enough oil the compressor will fail in time. The proper way to do this is to remove the Evaporator, Condenser, and Compressor and drain the oil out, then refill with the correct amount of oil.
But it's hard to remove a Condenser and/or Evaporator so many don't. In this case the next best thing is to flush those components (using AC Flush) then assume there is no oil in them, and then add a full oil charge along with a full refrigerant charge.