How do I upload my own theme/background?

[Moderated – please do not post in all caps – it’s considered yelling]

I’m a designer and songwriter trying to get my new website up to sell my songs and art. I’m praying it will bring in some income soon as I’m in terrible debt! I’m used to Weebly drag and drop which was so easy, but supposedly so limited compared to my new hosting company which uses mostly wordpress, Joomla, etc. and I have no idea what I’m doing. I don’t have any code experience, but I’m told I won’t need any to master wordpress. That better be true after the money I just spent! All I need to know is if I can upload my own background to start off my website building? I have a photoshop design nearly ready, but I don’t know the specs I would need, size, resolution, file type, whatever. Once I get past this stage, I’m on my way to learning how to upload context and set up pages. The tech support at webhostinghub, says I have to get all my wordpress consulting through this site, not thru them. So hear I am. Really wish I had a 800# I could call. But any help is some help!!! Thank you so much! Dee at Eaglesvoice