JOSM: How do I select an object?

I am obviously new to JOSM. I have been editing a while in the online-editor.

I installed Josm 17329 on Ubuntu 20.04. I managed to get our local custom trailmap as a custom tileserver.

I can’t figure out how to edit stuff, because I can’t figure out how to select an object.

I have presses s, clicked a path, doubleclicked a path, dragged around a path, pressed ss, and tried everything I could think of.

So how am one supposed to select an object in order to edit it’s tags for instance?

Thanks

Does the object become red?
If so, maybe you’ve hidden the side bar by pressing Tab? Here is where tag editor panel should be, if not closed.
Have a look at https://learnosm.org/en/josm/

Sounds like you did not download any data. This is done by default in iD but not in JOSM.

Bingo! Thank You for Your patience with a noob.

I thought I had downloaded, but apparently the area one can download is quite small. Also, read the error-messages slaps forhead