Drupal Commerce Kickstart Theming as an absolute beginner

I have spend days of reading through a ton of documentations & tutorials about theming. The topic is really hard for me scince I have never ever had anything to do with frontend. My knowledge about theming, HTML and php is basically 0, i know a bit of how CSS works.

Please dont ask why I start with front end development then, I just have to.

I would like to create a subtheme to the Omega Kickstart theme that gets delivered with Commerce Kickstart on Drupal 7. I have read a lot, but everytime I try to make use of something I thought I learned, I cant because something is different than in the theory.

I have started with creating a blank subtheme, that inherits everything from its base theme. So far, so good. Now I have no clue what to do anymore. I know about template files, that every site is put together using multiple templates and so on. But in Commerce Kickstart, all of the CSS and .tpl.php files are spread out through the file system in some folders like the modules folder. I have no idea what to do from this point.

For example, lets say I want to move the shopping cart on the left side of the header instead the right? What do I do to add a twitter feed on the sidebar and customize its look? How can I edit the .css of a certain element, when those are spread in 3 different locations in the modules directory?

If anyone has any tutorial specifially reagarding theming for Commerce Kickstart or has any tips i would be very thankfull!

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