I found a recliner beside a Dumpster. The bones were good, but it needed a new seat because the vinyl had holes with stuffing coming through. I looked all over online for instructions, but had to figure this out on my own. I hope this helps someone else. Total cost for this project -- $2 in upholstery fabric -- $3 for fabric glue -- for a total of $5, give or take a few cents.
Step 1: Measure the fabric for your seat.
For a recliner seat, measure the fabric larger than where you want to lay it -- leaving a 1/2 inch on the left, right and front. Leave about 4 inches of fabric on the back to glue and tuck into the back of the recliner.
The 1/2 inch edge on the left, right and front will be folded under, glued and stitched.