This is step by step tutorial on how to merge/combine two photos in photoshop CS6 or any other version of photosho like CS5,CS4 CS3 etc..there are many ways to do this but here i am doing this with the help of eraser tool.The process is fairly simple
1-open picture in photoshop cs6 then drag your second picture in photoshop.
2-Right click on second picture and select place.
3-Now select the eraser tool and delete the background of second picture with this tool.
4-thats it. you are done.