As I stated, the mass is in the skull itself, not in the brain. It states that the brain is entirely unremarkable. A mass and a lesion are the same thing, and there is one found in the skull bones. It is located just posterior to the choroidal fissure on the right which means that it it just to the right of the top of your head. They usually don't do anything for these since they are benign and aren't troublesome at all.
It doesn't say if it is inside or outside the calvarium or within it and about 1/2 inch across. It is just to the right of the top of your head. Think of the top of your head as wearing a beanie, and it is just to the right of where all the panels meet at the center. It may or may not have shown up on the CT scan, and would have been an incidental finding there as well. Some such lesions will grow, but the majority don't.
What you feel is probably too far down your head to be this. It is more toward the top of your head. This is absolutely nothing to worry about and should require no testing.