Plot

I'm frustrated. I need to make a layout for a school project, and i've never dealed with AutoCad before, i did pretty good at drawing i think. Then i used some blocks to fulfill my layout. Now i can't plot, it just shows a tiny green thing on the preview. I think i just messed up with the scale thing.

Please somebody could help me. I have to send it on Friday.
I need to make this layout a readable size image.

Ps: Sorry for my bad English! I'm Brazilian.

Thanks