Hi, please help me with my doubt if it is possible.
I would like to know how I can put a Image as background, to show in the render.
Don't in the viewport, but yes to show in the render, please!!! 
Thank you !!! 
use image plane
Ok, Thank you !!!
Now i would like to know how to put a video as the background. please!!!
To put 3D objects in a video...these things.
Thank you !!!
same wahy just chek the image sequence option... offcourse you need to make the movie file a image sequence.
Usualy its more convinient to use just a comp app, because its faster and has mucvh more benefits thatway.
If you have Unlimited you can use Live to quickly setup background then composite the rendered image with background footage in post.