I've been messing around a bit trying to get the hang of this thing. Drew some basic shapes. Right now I'm trying to figure out how to combine shapes and hitting a wall. e.g. if i have a rectangle and a circle and i want to combine them into one shape, and delete the section of the circle that is overlapped by the circle. Thinking it has something to do with nodes? I don't know ?
Is LibreCAD very similar to AutoCAD? If I get an autoCAD manual will most of the commands transfer?
I work in a shop that has a CNC router so I would like to learn this so that I can make DXF files for the router.
Try the LibreCAD User Manual before the AutoCAD manual. Note that it is still draft and may not match precisely the version you installed, but it will be close.
Also take a look at the wiki. You find more information there and a couple of tutorials.
As far as the rectangle / circle, it depends. If you used the "Rectangle" tool, you will have to "Explode" the shape and then delete the unnecessary line. Then you will need to "Trim" the circle. An easier option is to draw three lines with the "2 Points" line tool and then add an arc with the "3 Points" or other curve tool.