If the school has given paperwork, it should be complete. For safety sake, check the particular consulate you will be going to and make sure you have all required documents.
All consulates in this region will the 1 application paper you might need, there at the counter
You will need to get the paperwork from the school you will studying at. You will have to apply in person at the consulate in Cambodia, the visa will be ready the next day for collection.