[Q] How to point an engine on Linux.

Hi, I'm a bit confused about how to use the launcher on Linux. I had compiled it and confirmed that runs, but the only problem I have is that I have to point the launcher to some for it to recognize an engine, which in my case is GZDoom, but I also compiled it from source code. Since this is not like on Windows where I just have to point an .exe file, what file do I have to select o Linux? 