Rewriting single.php – wrong results

Hi all,

After having spent a week on building/customizing my website (I’m new to WP) I realized that the most important thing isn’t working: my Blog. I thought since that what WP is about, it would be just an easy addition, so I saved it for last, and now I’m feeling stupid for doing so.

Problem:
my template is coded in such a way that the single post page is just a full-width page, no sidebar, no widgets, no font-customization possible (unless I want to change the rest of my pages simultaneously).

What I have tried so far:
– Google informed me I needed to manipulate my single.php file. So I did that. Copied/edited other themes templates etc.. then added my themes “right-sidebar” template into it and it worked; however, partially. The sidebar appears under my post. How can I get it next to my post + change the background color and font?

I also downloaded the WP-Post-Template plugin to make new single-post templates (to select each time I post) but I can’t figure out how to get my preliminary custom-template (saved in folder with index.php) to appear in WP. What am I doing wrong?

I hope this is somewhat understandable. I don’t know what info you might need.

Thanks in advance for your help!!!