In reality you need a fur sewing machine...
However, you can do it by hand. I would use a stitch length of no more than 2mm.
You need to cut the pieces from the back, ie the none fur side, with a knife. Don't use siccors otherwise you will get a very noticable line at the join. When cutting you don't want to cut the fur, just the skin...So be careful.
Mark the stitches on the skin side, with a marking wheel.
Join the pieces with fur together and stitch them. It would be easiest in a stitching pony and if you don't have one then its v easy to make and worthwhile. Make sure there is no fur sticking out the sides as you are sewing.
Hoep that sort of helps.
Alex