My computer is listed as offline

I am new to TeamViewer, having been a **Third Party Product** user for years and this seemed like a similar interface but I am not finding it quite so user friendly. My TeamViewer lists my host as offline, I see nowhere an option for going back online and don't even know why I'm offline. I thought I would completely uninstall, I'm told a version of TeamViewer is running, but I see no version running anywhere and now the TeamViewer icon is totally gone from my sistem tray. If I try to open it from the Windows Start-up I get a message saying it is already running and have no clue where. I don't think I like this app.