I have St. Augustine Grass and i wanted to know how can i make grass grow in the spots that don't have grass without going and spending money on grass seeds? I don't want to go out and buy some.

Buy sod...never seen St Augustine grow from seed.

You may need to check PH of soil where the grass is not growing....it may need some lime added to raise the PH.

Take cuttings from your grass and replant them wherever you need.