Hi Barb,
I do not sew, but my friend showed me how to do it myself. Pop the chair cushions out and put your new fabric right over the old fabric. Have a staple gun with you and make sure the fabric is taut and evenly pulled as you staple. My friend and I completed the chairs in 1 hour.
You may also want to go to HGTV and look online.
Other wise I can not help with an upholsterer.
Good Luck!