Need help with splitting audio for streaming.

Title explains most of it. Not sure if this is the right section to ask it in, if it's not sorry. I use OBS and I want to be able to split the audio so only I can hear my Skype audio and so that my stream can't. I've tried looking up guides, but they haven't worked for the set up I have. I have Windows 10 with Realtek HD Audio manager installed if that means anything. I'll continue to look for guides after I post this, but if anyone has done this and can possibly help me, just pm me or reply below. Thanks for reading .