I don't understand the "middle of the page" - just eyeball it!
Depends on your CAM software. What filetypes does your CAM software accept?
Most will accept dxf if not ipt or stp.
File>Save Copy As type.....
It sounds like you have not yet created a 2D drawing (*.idw or *.dwg) of the 3D model.
File>New and select appropriate *.idw template.
I recommend that you go through the Tutorials.
CAM software (Computer Aided Manufacturing) creates machine toolpaths CNC-Computer Numerical Control (otherwise known as g-code) from your solid geometry.
Inventor uses 3D models to create 2D drawings. You should spend time reading the links posted by JD
...I have made a 2d drawing
Attach your 2d "drawing" file here.