When all of the mains have been strung and tension pulled, you will need to tie a knot.
Don’t remove any clamps until the knot has been tied or you’ll lose all that tension you just pulled.
Insert one end of the string into the closest possible grommet with space on the outside of the frame and pull the string back inside.
If a grommet is too tight, you might need to use your awl to widen the hole and your pliers to pull the string through the grommet. Don’t be too aggressive or you might damage the grommet.
Bring the end of the string around one side of the main and up the other side of it forming a loop.
Hand pull to tighten. Repeat the process to create a double knot for that end of the mains.
PRO TIP: Until you’re done with the crosses, have tied all your knots, and inspected the racket for errors, don’t cut the extra string. It wouldn’t be fun to redo any stringing, but if you have all your original/excess string, you CAN do so.