How to make Composites:
Start by downloading a good software, Photoshop is preferred but if you don't have the funds, go for www.paint.net it is just as good and 100% free

1. Using regular paint turn everything but yourself into a solid colour
   
   save it as a BMP so it will be crisp when you make the solid colour transparent later on
    
2. Open this pic in paint.net and make everything but yourself transparent, using the magic wond
   
   Click on the solid color then press "delete" on the keyboard so it looks Like this:
   
    
3. Go to Edit > Select All > Edit (again) > Copy . Go to the desired background where you want to paste your picture and then click Edit> Paste into new layer, like this:
   
    
4. After you adjust yourself into the right position, adjust the brightness and contrast, or anything you like, play around with the effects till you find something you like. Just go to Adjustments or Effects.
   
   
   Et Voila! :)