download photoscape , its in there !! http://photoscape.en.softonic.com/ photoscape is a free editing program and it is easy as to do the collages in there.
I use Photoscape too.. it is awesome and very very user friendly.. and they have a ton of collage templates to use,, they also have a rather good edit program , with lots of different features . and its free, which I love!!!
I use Picasa because it is so versatile, completely in the hands of the user and not tied to a selection of fixed layouts. It is also very easy to switch to Picnik and back again to enhance individual elements of the collage. I use it extensively and have found nothing to equal it - at any price!