what software may i used to change the clothes of the subject?

Answer 1

I am trying to figure out exactly what you mean ...

Are you wanting a program that has a human figure, and clothing images, that you can place on the figure digitally? i don't know of any offhand, but there should be some modeling programs available, google "clothing model software" or similar.

Or are you wanting to take photo's of your own and change the clothing on the image? to do so you would have to either have photo's or images of the clothing then place it on a layer in an image editing program, OR have hand drawn images of clothing to do the same, OR paint them on.

Any image program will allow you to do the latter, and here are a list of free ones:
http://wang.zhenzhou.googlepages.com/
http://www.photobie.com/
http://picasa.google.com/index.html
http://www.plasticbugs.com/index.php?p=241
http://www.freeserifsoftware.com/software/PhotoPlus/
http://www.photofiltre.com
http://fileforum.betanews.com/detail/PaintNET/1096481993/1
http://park18.wakwak.com/~pixia/