Please, help me configure nekobox to proxy only certain apps.

I'm a complete noob when it comes to networks in general and VPNs specifically. I tried seraching for guides on configuring nekoray, singbox or v2ray but found almost nothing. So, can somebody, please direct me to something I can read to understand configs or help me get what I want.

The thing I want the most now is directing discord via proxy and all other apps bypassing it both on linux and on windows. I found some old guides that made something like that via routing or TUN settings, but they don't work for me.