Quote - Are these images not the same as any image that i can get of the internet?...or out of stock images?...and then in photoshop put my character in front of them?... is there a way to make your characters appear like they are part of these backgrounds?...

http://www.renderosity.com/mod/bcs/vt05-swamp-tales/92754

The backgrounds you linked to are just flat images, so although the HDR / Environment Sphere approach is the best for getting integrated lighting, it won't work for these.

Render your character to a PNG, and in render settings choose a black background. Then, as you say, composite in Photoshop. The trick, of course, is to set your scene lighting to match the apparent lighting of the background, and that can be difficult. You will probably want to do a "shadow catch" render to give you a ground shadow also.