What is the computer operating system that you are running Premiere Elements 12 on?
If it is Mac, you do not have Chroma Key, Blue Screen Key, Green Screen Key. You should have Videomerge.
But, I have been directing Premiere Elements Mac users to my blod post to the Difference Key as a subtitute for green
What is in that blog post also is applicable to Premiere Elements 12.
Here the Adobe description of ChromaKey...please scroll down in Effects References to see the description.
i have windows 8, do not have the program yet... I am thinking of buying it, but i need to know it has that option
You should do well with Chroma Key in Premiere Elements on Windows 8 64 bit.
Adobe marketing or one of the program's users once described Videomerge as an automated Chroma Key and commented how much better Videomerge is. That never happened for me. Chroma Key is the winner for me.
But there are a lot of factors in your specific image which will factor in how good or bad the key will be for you.
Please do not hesitate to ask if you need clarification on anything that I have written.