really dumb startup question

New user. Downloaded wine, winebottler, and librecad. No issues. How/where is Librecad executed?

Welcome!

What OS? You don't need wine, LibreCAD is open source.

LibreCAD is in many Linux distributions repositiries, for example I use Debian, installed LibreCAD 2.1.3 using apt. If you need newer, you need to compile it.

thank you.

Ha!  You think YOU have problems!   First of all, LibreCAD refused to allow me to register making me change password many times.
Now to my major problem.   I was an AutoCAD user for twenty + years and had it singing and dancing for me.
I cannot get LibreCAD to do much of anything at all.   I recognize the software is excellent and the fault is mine, but the manual seems incredibly opaque and dense.
Wonder if there is a 'LibreCAD for Dummies' around.  I used to design electro-mechanical aerospace and nuclear mechanisms.   Now I couldn't figure out a 2" X 4"
Any suggestions are most welcome.

john wrote

LibreCAD refused to allow me to register making me change password many times... the manual seems incredibly opaque and dense. ... I used to design... nuclear mechanisms.

I hope the manual was well documented for them.

Have a look on the wiki under manuals and there is an alternate one for dummies written by a community member.