My language skills in general are very low, i have problems to form sentences, each sentence is a frustrating fight not won at the end of the point. Nethertheless, i would like to prove myself being able to write a whole fiction. But, in stark contrast to many writers, i do not have a good memory and i am loosing threads constantly. Therefore i ask, if there are graphical scheemes or flowchart or sth. similar that helps to plot the keep the wordless semantics in one big chart, so that once this graphic representation is made, i just need to fill it out with words in analogy to a sketch artists use.
You want to avoid software for this. Creative people swear by analogue tools. They seem to facilitate both creativity and understanding.
Whenever I see a graphical representation of a plot made by a well-known published author, it looks something like what J. K. Rowling did for Harry Potter – a table, drawn by hand on paper:
There are many examples like this on the web, all of them handwritten (and hard to decipher). If you are one of the few people who work better digitally, here is a an example created by a fan for the movie Return of the Jedi. Since this is more clearly readable, it will also make it clear what this kind of table is about:
In this example, the rows represent important aspects of the story, the so-called "throughlines". This can be characters, relationships, or any kind of thread running through the story. In a detective story, one throughline might be the riddle that the protagonist has to solve; in a love story it will be the development of the relationship between the two main characters. Usually the throughline will be the development of something: a character, a relationship, understanding of a problem. In Kim Stanley Robinson's Mars trilogy, one throughline would be the terraforming of the planet Mars.
The columns then are the different turning points and other events. Rowling had these as rows (and the throughlines as columns) and labelled them with dates. The Jedi example gives them names from screen writing theory ("inciting incident", "crisis" and so forth). How you label them will depend on your story writing theory and on the narrative structuring of your novel.
You can also draw relations, influences, and effects, from one table cell to another in colored arrows, or shift persons from one throughline to another (for example, when a couple split up and one of them starts a new relationship, or if in the Lord of the Rings the Ring is given to another bearer).
If you write something that has multiple threads that develop through mulitple events, this tabular representation feels quite natural to me. I had independently developed this system for myself when I was writing my first long narratives thirty years ago, and I strongly suspect that the others who use it have not all learned it from one single teacher but mostly have also found it by themselves.
Here is one by Normal Mailer for Harlot's Ghost:
And here is another one by Joseph Heller for Catch-22: