Now I can draw! Thank you so much

I'm new to SketchUp, and are looking forward to use it, BUT I've no idea how to start drawing!! I have the newest version (7), and choose architectural design-feet and inches as template. Then I get a totally blank page (with the tools) I start drawing with "line tool" but no line shows up. Neither if I try the rectangle or circle tool. What's wrong? I wonder if I also miss a sort of coordinate system (x, y and z)with a man placed in it. I've seen this on several videos on You Tube etc.

I will be very thankful if someone could help me with this problem...