How to Design Custom Page Template

HI There!
I spent the whole day yesterday to create a Custom Page Template that now appears in my Editor. I also used a little bit of code from the page.php so the static page that I intend to have on front of my blog looks good in the preview so far.

Here comes my issue:

1.I don’t know how to design the template properly. I was able to insert some lines, links, headers etc. due to my little HTML/CSS knowledge.
(I edited directly in the Editor)
But somehow I failed inserting a background color for my static page template. I tried it with HTML/CSS and PHP but it didn’t appear.
Also looking for Template Tags on WP didn’t help me out on that.

-> How can I fix this problem? (Best would be with HTML/CSS)
Please consider that afterwards I want to insert pictures and buttons for links as well.

Thanks in Advance!!