It's not a task suitable for a complete beginner. You'd need to install the OpenWrt SDK and either use the toolchain to compile it as-is, or package the app properly for distribution.
Before you ask: no, I'm not going to hold your hand through the process. It's too much work.
isn't there any Youtube video for compiling opkg packages?
This is the video for the whole custom OpenWrt Image, don't know how useful it can be for a single package.
But it's not an opkg package, it's just source code. Compiling already packaged stuff is easy and OpenWrt isn't really much different -- the hard work has already been done.