Upholstery and Fabrics - Can't Find screws to reupholster chair!

So I bought these fantastic four dining chairs, thinking that I could reupholster them. I have read countless sites and thought that it would be a cinch! But I have already encountered a problem - I can't seem to find the screws that need to be removed to take the seat cushion off :wall: ! It's always step one, so I've been a bit frustrated. I have taken some pictures, hopefully someone can tell me where to look for these screws or other optionon reupholster the chairs.

This might be a silly question, but any help would be greatly appreciated. Otherwise I might just try giving the seats a good clean.

http://farm4.static.flickr.com/3274/2610025766_b31e1278b3.jpg
http://farm4.static.flickr.com/3190/2610027708_d928e42313.jpg
http://farm4.static.flickr.com/3098/2609198997_a94a875d83.jpg

Hi and welcome to the forum!
My chairs have a similar setup and the screw is in the bottom of that angled, triangular piece of wood on the bottom of the chair (3rd pic). What is that circle at the bottom of yours? See if you can pry it out. Could be the manufacturer put a wood plug in to hide the screw. Let me know if not, I'll try to find an answer.

You may have already found out it does not come off like the seats you are thinking of. It is stapled under the gimp (the trim). Undo the three sides and the material will lay to the back there is a cardboard strip under to make the straight line.