Compile and install an app on openwrt router

Compile and install popular app on openwrt router while guiding me (holding my hand) through the process. I have programming background, (from looong time ago) but am not familiar with Linux. (A few weeks ago I didn't know what all of this means, and how to ask this queastion:) I figured out how to cross compile "helloworld" c example program for my router with provided toolchain. (I have development system set up:) I need a more complex program compiled and installed. I need support because I have a full time job which is completely unrelated and also I'm a single dad, so it's really difficult to switch and concentrate on the subject. Instead of wasting hours on solving dependencies (see, I'm getting the drift:) and looking up what an error message means, I could use some help. This app is no longer supported, but,it is still very popular, so there's sufficient documentation. And also, someone updated the code to work with qt 5 (whatever that means:). If you can do this, I'll reveal the name of the mysterious app over a secure connection:)