heylo,
here's an easy 3 step 2 themes:
1. go to the My Home menu on the top right hand side of the screen under the search bar, then click the last item in the menu: Account
2. Click on the Customize the way Chess.com looks... under Styles & Themes, some where in the middle of the page
3. Now u can choose different themes (i suggest bleachruto by k05;)lol) or to make ur own, there is a box top left that says Browse All Themes w a down arrow after it. click the down arrow and select Create a New Theme.
I hope this was helpful, lemme kno how it goes & have fun w it:)
It is said that as a gold member, I can create one BG theme. But how to cteate it I have no idea... can't find this in any help topic in Chess.com.
Nick Chong