I cant extrude (noob question) I'm watching a tuttorial and I am trying to extrude the line between two points by selecting the two points, and hit E. but it looks like that and ı cant go on.
You are doing this in Solid View so you are not able to select the dots behind your view.

To solve this issue go to Wireframe Mode by pressing Z and now you can select the dots behind your view, but not with click select the dots with circle tool. The short key is C .