You have to go through a retailer that participates in the GSSF discount program. For Nebraska, unless you are an LEO, you have to go through GT Distributors in Texas. You can call them and ask them about their GSSF Program information. Then, they will have you send FFL information to them for the transfer and they will sell you a gun. You need to check with them to see what they have in stock for the GSSF program, or they will put you on the wait list. It is not the most efficient way to purchase a Glock, but it is cheaper. If you don't want your gun for SEVERAL months, you can go through Glock directly, but that takes a long time!
Good luck!