Go to http://www.picmonkey.com/
Select the collage option
Insert the images you want to appear in your picture collage
Click on an image and drag it into your picture collage
Select ‘layouts’ to change the way your picture collage looks
Select ‘background’ to change the colour of your background
Once you are happy with how your images look, select ‘edit’ as this will allow you to add text to give your picture collage a caption
Click the ‘add text’ button
Type your text and use the font/size/colour options to change it to suit