In 1985 (I have just looked inside the book to see!) I bought "How to Restore and Repair Practically Everything" by Lorraine Johnson
it ahs detai455led instructions for doing all kinds of things and I have used it a lot. I have just looked it up on amazon, and the 10 May 2004 edition is on there for a peeny, plus postage! There are other editions too, at various prices, none of them all that dear.
It doesn't mention staple guns, but we recovered and revarnished two fireside chairs using one. We took off the old cover, but kept the padding underneath. Then we (well, DH mostly) sanded the old varnish off, and I put new polyurethane varnish on it.
We cut a piece of fabric larger than the padded back, and long enough to go under and a few inches up the back. We laid it on evenly and and pulled the top over to the back and stapled the top edge an inch or so down, then each side was wrapped round to the back and stapled an inch or so in - that really needed two people, one to pull and staple, the other to hold the fabric with the pattern even, as it pulls out of shape easily, but it could be possible on your own.
When we got down to the arms, we didn't cut the fabric, but folded in that bit and then took the fabric under the arm and continued stapling, and at the bottom of the back it was taken under and up the back, side edges folded in to fit, and stapled.
The cover for the back was laid face down onto the front of the back (IYSWIM) so that a couple of inches hung over to the back, and that stapled near the top edge of the chair. Then we folded the sides in, to match the width of the back and turned the fabric over to hang down the back. Then it was just a matter of stapling it down near both edges and folding in the extra at the bottom before stapling it.
It was straighforward enough to sew a cover for the cushion.
hope this helps - Ask if it isn't clear.