Excel formula several OR

I'm having a problem that I looked on several guides in order to understand OR statement.

=O(W6>=100;W6>=90;W6>=80;W6>=75;W6>=69;W6>=40;W6>=20) 

this is my formula, like that it returns true, the thing is I don't want a true writed in the cell I want to write something like "Good", "Bad", etc. I tried to write in the formula cell but it keeps sending an error.

Please help me out