I have been writing on my first book for a while now, 3 to 4 more planned, and uhm...I have no clue about what to do next. Does anyone know anything about companies, that publish books, or does anyone have a good advice?

You'll need an agent to break into traditional publishing and -- Catch 22! -- no decent agent will touch you until you're established.

You can self publish on Create Space and sell through Amazon-KIndle. The only expense you'll face is having a cover done and that doesn't cost much. Check my profile page.