How to resize blog/background image?

Seriously?! No one knows?!

First you need to correct your code here . . . https://validator.w3.org/ which will then makes changes easier to do.

Alright. I’ve never heard of that. I have alot of errors apparently?
https://validator.w3.org/check?uri=https://www.themarque.org&charset=(detect+automatically)&doctype=Inline&group=0

Now what?

Choose a different, narrower width theme.

That’s really the only option? hmm

Noooo… you can look at the output of the validation and CORRECT them. Each is identified by like and the reason for the error clearly noted. So FIX them and see if that fixes your site. If not – you have the basis for another question that might be able to be answered here. Nobody can offer an opinion on what is wrong with your site and a cure until you do what you have to do first – which is …. (do I have to say it again?)

That’s really the only option? hmm

That’s not the only option, but unless you are really good with css and theme design it will be, by far, the easiest. Your header and content in that theme is set to 950px wide…the header image is 1300px wide. You’re going to have to do a lot of theme editing to get it narrower and you will probably need to change some of the layout as well.

Well, I just shrink the header then?

No, it’s not that easy. If you don’t know how to edit a theme, then you need to get into it, click around, experiment, and learn…or find a theme that is not so wide and will fit your needs.

Alright. Thanks.

Experiment time.