The line has to .095 or smaller, .085 is ok, but doesn't take a beating like the bigger stuff. There are two channels in the line spool. Each channel feeds one line hole in the head. Take about 20 feet of line, thread it halfway through the hole in the base of the spool center rim. Slowly and evenly wind each length of line into one channel, making sure it is kept even and make sure you are going in the proper direction. When each channel is full lock each line into the slot at the outer lip of the hub, leaving at least six inches of line free. Bring the hub up to the cup, threading each line end through one of the holes in the hub, then snap the spool into the hub. Take a pair of pliers and yank each line end out of the clip hard. If you did it right it will work. If it doesn't, you are now part of the club and will have to practice.