First of all, your screenshot is of the Premiere Pro interface. It looks like you have your robot on one layer and your background footage on another. Adding layers together is called compositing. After Effects is a compositing tool. Premiere is not. AE is for compositing, motion graphics, and animation. Premiere is for cutting clips together - also known as "editing".
I can't really see enough in your screenshot to offer a suggestion. There is nothing in your scene to match anything to. I can't even tell what direction the light is coming from on the floor. One thing that helps is called a light wrap, but, again, you can't really do that in Premiere as easily as you could in After Effects.
I think I tried to use after effect but i had difficulty adding the background footage which is why I changed it to adobe premiere.This was done awhile ago and I was nt sure how to go about it so decided to ask around. I shot the alien in front of a green screen and tried to add my alien to this other footage. I think Ill redo the whole thing all together and use after effects. Thank you so much for responding.