I was reading a tutorial and the first part said
Open up Blender , select the default plane, enter edit mode(TAB), and by using simple extrusions (e) create the outline shape of your ship from top view. You can just do one side then duplicate(shift+d) then flip (s then x) your vertices and then select all(a) and remove doubles (w>Remove Doubles).
Now when i pressed (e) it says OK? and I hit extrude. When I do that it says “No valid vertices seletced” and dosent let me draw the outline
Can someone tell me how I can fix my problem, any help would be great.