(I might suggest proof-reading some of your posts beforehand - I have dyslexia and its rather difficult to read, sorry)
There are no "solid" guides to making a theme, just as of yet, but here is a general overview;
Your theme is located in its own folder inside the "templates" folder of the script. Each theme needs three files - one css file (style.css, main.css, whatever you want to call it), one header.tpl (which contains everything about your theme from <html><head> to </head> and everything in between) and one template.tpl, which contains your body (<body> to </body></html> and everything in between) html and css.
The script then has a number of small codes that are placed throughout your template - for example, {$browser_title}, {$document_content} or {$sidebar}. I would highly recommend sniffing throughout the other template folders already installed with the script to see how they are structured.
To make the theme itself, you just basically make a standard web template that fits your idea, place it into the header.tpl and template.tpl files, put in the key codes and you should be okay, provided there aren't any glitches.
A good place to start if you aren't that great at making themes from scratch is here;
http://designshack.net/articles/css/715-awesomely-simple-and-free-css-layouts/
Other things to google to help you build the layout is "colour scheme generator" or "colour scheme palettes" for your colouring needs, "free tile backgrounds" for tiling images or backgrounds, and generally anything you're stuck on - the internet is full of css/html tutorials.