there are a few people on here wanting to do there own seats so here goes
start by striping the seats
cut the hog rings out as they will need new ones when you fit the new cover your going to make
once all the covers are off look at the panels to see how there put together mare them with 1,2,3etc if you wish then undo the stitching
put the panels on your leather vinyl or cloth and draw around it . then cut it out ..and make sure you do the right size
when i do leather seats i glue a 1/4" foam under the leather . again glue and cut around ....good carpet glue is good for foam
then start to sew ......use a good sewing machine you can pick one up for around 400 in ebay dont use your mums . grans it no good
all im doing now is sewing it up how it should be also ive added some white piping

this is a bmw seat im doing for my saxo but a seat is a seat
there will be metal rods that you have to put back in the new seat covers . these are used to connect back to the foam using new hog rings these also can be found on ebay
once you have sewn all the panels up and plastic clips , rod e,t,c you will know where all these go cos at the start you looked where they came from lol
. the panel back on the seat butting it back is the same as you taken it off
so things needed
1. sewing machine leather you will need one with a walking foot
2. 1/4 foam if needed
3. tools to take seats apart
4. hog rings and the tool for them
5. carpet glue
6 sharp blade
and plenty of time . my seats where 12. to 14 hours for front 6 to 7 hours on rear
good luck all

sorry if not a great step by step but i tryed