How do I position title, frametitle, navigation bar and contents in arbitrary absolute positions?

Question

I am trying to adapt the structure of a slide in beamer in order to match a background I would like to use. However, if I just insert the components of the frame (title, frametitle, contents), things end up off center, or there's a lot of unused space. I am not using a predefined template.

Searching for this found a few related answers, but I could only get this to work with the frametitle. I positioned it in an absolute position using textbox, and although the color had to be set within the textbox, this worked fine enough:

\setbeamertemplate{frametitle}
{
   \begin{textblock}{1}[0,0](0.02,0.04)
         \color{white}{\insertframetitle}
   \end{textblock}
}

However, I can't get this to work to position the title (code similar as above has no effect), and it doesn't seem like it will work for things like the navigation bar, which would need to be repositioned as well. Is there a way to do this?

I have been searching for this for a while and none of the answers seemed to address this, sorry if it's a duplicate.

Edit: This is what I got so far:

What I would like to do is bring the presentation title up, and center it in the dark green rectangle. The structure in the slide I would like to get is something like this:

And the topics and subtopics would be the navigation bar, but divided into 2 parts. But the main thing I want to do is to divide these parts into those boxes (frame title, content, navigation bar).

Answer 1

To customize a theme take a look at the .sty files of the default themes of beamer. This will give you an idea.

1. Look for\defbeamertemplate{title page}, \defbeamertemplate{footline}, \setbeamertemplate{sidebar right},etc.. Those let you position and customize the regions on the page.

2. The elements that you put on the title page for example are called by commands like \inserttitle, \insertauthor, \insertframetitle. Again look for them in the defualt .sty files. There are a lot of resources online where you can read the theme files in your browser.

3. Here is a list with different "beamer colors" that are used in themes. You should make use of those when setting or defining a template.