http://www.picmonkey.com/
Pretty easy to use and figure out. It's free and you don't have to sign up/register. Do you know how to crop your photos?
After you've cropped your pics to the same size and saved them, choose Create a Collage from the home page.
Choose the symbol on the far left that has 3 boxes. It should say "Layouts" when you hover your mouse over it.
Click Ducks In A Row and choose how many boxes for your collage.
Open the pics you want to use and drag the pics into the approprate boxes.
Move the mouse to the top edge of the frame, until you see it change into an up and down arrow symbol.
Hold the mouse button down and increase the frame size to fit your photos.
Then save. You did it!
Hope that helps.
