I'm just starting Illustrator and when i created my logo, I saw that I can't fill the areas with color or some areas are not like i want them to be and it's just weird how they are filled. Idk how to fix that. I used the Ellipse tool and pen tool to create that logo. Thank you for your help! : https://i.stack.imgur.com/bdiZ6.png : https://i.stack.imgur.com/h7fBG.png
You are lucky - you work with Illustrator. If you were in Affinity Designer or Inkscape the things would be harder. In Affinity Designer you would need to redraw nearly all to get the wanted fillable areas or at least draw and join numerous new parts to existing curves to get closed shapes. In Inkscape it's often possible to recombine the paths with minimal redrawing, no matter are they open or closed.
My suggestion: Learn how to use Illustrator's Shape Builder tool. It's easy although it's not an effect which could be removed later. It literally builds new closed shapes from existing edge shapes. The edge shapes can as well be open or closed paths.
Other possible tools: Live Paint and the Shaper - more complex, but they do not work destructively.