Crelly Slider

Hi Guys, I am using the free version and trying to USE crelly slider as my header image. I am not sure where to insert the short code. I tried to add a new row, text widget and put in the code but the image is not full width. This is what it looks like.
https://prnt.sc/bwegkp

I am wondering how to remove the padding to make it full width, or better how to insert the short code to replace my header image. Thank you in advance!

P.S, if you can also give me a code on how to remove the padding on all parts of the website, because when i try to put in an image background for lets say the services area, it also has a padding and does not look nice.