Upload you pictures onto Photo bucket, then edit and re-size them.
To get them as your sig you need to copy each IMG code and paste them.
It's not a 'proper' siggy in the sense that they are all individual photos but I don't think it matters really, mine is made on photo bucket and although it is a bit plain and boring compared to other sigs I like it as its easy to make and easy to change (can also change/remove one picture at a time rather then having to start again with it.
Hope that explains it well enough, if you want anymore help just let me know.