I can't use any types of "Access Modifiers" in may "Class". If i try to use for example "Public" or "Internal" it comes with fail-code's "CS1519" "CS0106"

I tried to make a "Method" in my "Class" but I couldn't make it visible to my "Program.cs" because my "Class" gave the failcoat and came to look like in the picture.
I hoppe someone can help me.
At this level you aren't able to apply any access modifier. This level is the level of local methods which are accessible from the method contains them. Thus, any access modifier has no sense.
If you need to add another method to the 'bil' class, you should put it after line 20.