vertical lines

I'm a beginner with librecad 2.1.3
I don't manage to draw vertical lines

Do you mean the command "Vertical Line"? Watch the Tools Options Bar and set the length.

If you just want to draw "by hand" you can restrict the movement to vertical.

Or in the command line next point "@0,something"

Please explain the problem more detailed. You should study the manual. It's a bit outdated, but still useful for the basics.