ok, im at my nans PC, so im doin git straight off my head so im sorry if its not totally right! and also i wont be able to do screen caps or whatever they're called!
ok, first open a new siggy making sure its 550x200 or smaller, then click on the text box (A) and choose your font, it doesnt matter about size or colour! then spread the text to fill the siggy space.
then click on the magic wand button which is on the same button as the free hand 'wand' and the box (i think its like 5th from the top on the toolbar on the left) then click outside of the text on the siggy. it should all go fuzzy. lol
then cut our the pics you want to use, i found that it was easier to have a pics per letter so try and do that. this bit also took me ages to get the right size, but dont worry you'll get there.
once youve cut the pics, place then exactly where you want them (you may find you need to alter the size again) and once all pics are in place, click layers, merge, merge (something visable). then go to edit, cut. the pictures should then be cut out to shape the letters.
then save the siggy as a jpg image. then close the siggy.
then re open it and click the fill button which is above the 'A' on the toolbar on the right. then pick a colour that isnt in your siggy, i always use a really bright green, then fill the background with the green.
then go to image, pallette, set transparency (a box might appear saying you need to decrease the colour, just click yes) then click on the second dot and make sure the colour is the same as the colour youve filled the siggy with. then click ok.
then click image, pallette, show transparency and the siggy should then be transparent, save the siggy as a gif or otherwise it wont work, then you should be done!
im really sorry if you dont get me, when i get home ill make sure ive explained it right!