ok its real easy. minimize the craigslist page.
go to your pictures and open the one you want and then right click on it and it will say OPEN WITH...
click on open with paint. then it will open up and then on top where it says file, edit, view, image, ect...
you click on image, then strech and skew
then you going to adjust the skew
it will say
all you need to change is the 100%s on both to like 30% or 50% depends on what size you want.
then save it and thats it. then continue with craigslist posting
let me know if this works if it doesnt I can try to walk you through it better.