FOR Step
You could try some of the stuff on
http://www.download.com/windows/
And try some of the Digital Photoshop or Graphic Design Software.
I use JASC Paintshop Pro 8, which came free with my PC when I bought it, My mates use MGI photosuite or Adobe Premier but they are serious graphice designers and think Adobe Premier costs a few grand to buy!!!!
Found this link for you
http://www.soft32.com/Download/free-trial/Paint_Shop_Pro/4-344-1.html
I don't know if there's a guide for for creating PNG's to add to this site,
in one of these forums, if you've used any image editing stuff before, you should be able to pick it up fairly quickly, I picked it up in about 30mins, I found the trick is to use one of the images that's already on one of these threads, then copy the images you want over them as a new layer (but good idea to make sure it's copied as a transparent layer), then delete the bottom layer, which should leave just your stuff on there, save the whole image as a PNG file, and paintshop Pro will merge all the seperate images into one layer, which will in effect be slighlty lifted from the painting surface.
I generally use the old Microsoft PAINT to change the colours of logo's etc, save the image in that as a 16colour image and then using the fill effect to change the colour, and then open that image in paintshop, then copy and then paste as a transparent layer, then adjust the size using the deform icon, it should ask you a question along the lines of do you want to create this as a full layer? you click yes, then an red square will appear around the shape which you adjusted in a similar way to adjusting pictures on WORD documents.
sorry if this isn't clear, i'm not particulary good in explaining things like this in writing, and if anyone can give this chap any further guidance on what to download or how to create these kit images, Im sure they would be grateful.
If there is a kit that you desperately DESPERRATELY can't live without it, let me know and I'll see if I can find it for you, i've got about 150-200 PNG's saved now, and working on others, just haven't got round to getting them on Imageshack and uploaded onto this site, and if I haven't got it, then I'll try and have a go at creating it for you, if it isn't too difficult, and it's NOT a Man Utd, Liverpool, or Chelsea kit your after.
Have a Free WROXHAM FC kit on me, changed the sponsor to the Norfolk Broads famous ROYS OF WROXHAM (artistic license used there), C'MON THE YACHTSMEN, you can win the Ridgeons League Premier Division!!!
Then you need to get into Imageshack to upload them onto this forum. But that's for later once you've created some kit's.
Hope you get creating and you find a decent free editing program to use.