Dimensioning

Just downloaded the program and started working through the tutorial.  Draw a simple rectangle and try to dimension it and I get either a new 3 sided line attachment with no dimensions or nothing at all.

Tool > Dimension > Horizontal

Turn on "Free Snap" and "Snap on Endpoints"

Left Click on the Left Corner, Right Click on the Right Corner move the mouse to a third point and left click.
Right Clic to Exit dimensioning.

1.  I either get nothing, or
2.  I get 2 new vertical lines and a new horizontal lin but no dimensions

Any suggestions?  Thanks

Your procedure looks allright. Maybe a matter of sizes. When you get 2 verticals and one horizontal, zoom in and in until you might find some very tiny dimension and ticks or arrows.  

As a new user, I can confirm you must go into the Options --> Drawing Preferences --> Dimensions and fix up all the defaults. Generally set them all to 1 for a start. On Windows 7 and Windows 10 systems they are all super small decimals after you first install the program.

Ken