Help with editing image

hello Friends
I am trying to put a shining effect in my club’s logo image. as I seen in the tutorial that firstly I have to select the portion which is required to be offered for a shining effect. I am trying to select the outline of the image with line tool and trying to fill it. But couldnt do it, it remains with some gaps(I think so) which are not visible and leads to NO COLOR fillup.
Please help, is there any tool by which a particular portion can be selected? I am trying to give a shiny effect (reflection with a running light) to an image which is somewhat similar to biohazard sign.