Quote: I have this carpet for background, but it's not in the whole screen, I would like to crop sides instead of having to use focus to cover out the edges. Is it possible?

Don't see why not. If this is a still image, drop it on to the timeline and select it. Then click the CROP IMAGE button.

Another method, rather than crop the image, you can resize it, as well as video, by dragging the corners/edges/sides till it fits to suit your needs. Cropping may well reduce the quality of the image also.
Maybe try a 3rd, way, right-click the image in the timeline and alter the aspect ratio. HP Envy Phoenix/4thGen i7-4770(4@3.4GHz~turbo>3.9)
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Quote: I have this carpet for background, but it's not in the whole screen, I would like to crop sides instead of having to use focus to cover out the edges. is it possible?

When I use an image for background not full screen, the first option is to zoom the image.
Select the image in the timeline, preview appear in the balls at the edges, I click on the ball and stretch the image up to fill the screen.
In some cases I open Pip Designer I have more options, like clear the aspect ratio. AMD-FX 8350 / 8GB DDR3
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