Trim any stray fibers or rough edges around the spot that needs repairing. Do not take away a lot of the vinyl, just enough to create a neater edge. Use sharp scissors.
Measure the tear or hole and add a 1/2 inch to the measurements.
Cut a piece of heavy vinyl to fit the new measurements. Weatherguard vinyl is ideal but if you can't find it, use a heavy, exterior-grade vinyl.
Apply a line of liquid, vinyl adhesive around the edge of the bottom side of the vinyl.
Press the patch against the glue so the fabric is Weatherguard vinyl is sealed shut as much as possible.
Tape the patch in place using painter's tape and leave it to cure for 24 hours, or as recommended on the adhesive's instructions.