So there’s two ways, one way works- and one way is the right way.
The way that works (but not the right way): you’re hooking up your mic to the mixer- that mixer should have a MAIN OUT (left and right)- you can get a RCA to 3.5mm (headphone jack) adapter and plug that in to your microphone-in on your computer. HOWEVER, this is called “high-impedance” and will create a “high signal to floor noise ratio” or in layman’s terms- a BUZZ.
The right way: get an audio interface that works with your mic, this will have a USB out- and take the direct signal from the XLR mic, and output it to your computer using USB. This is a direct connection, using “low-impedance”. Try Focusrite or M-Audio, they have some pretty cost effective interfaces that’ll work with PC and Macintosh alike. Here’s a link to my recommendation. Scarlett Solo 3rd Gen USB Audio Interface with 10ft Guitar Cable https://www.amazon.com/dp/B09P8X5KTP/ref=cm_sw_r_cp_api_glt_fabc_PA3WVJH2CK3Q7EWVMJBX?_encoding=UTF8&psc=1
A good interface would be the focusrite scarlett
What's your budget?
Assuming you're recording YouTube videos in your room or at your desk, a shotgun mic is normally a good choice since it doesn't pick up as much of the surrounding sounds in your room. It has a more narrow pickup pattern than the CM25 or similar cardioid condenser mics.
However, for any kind of XLR mic, you need a preamp/interface like the Focusrite Solo to convert the audio from analog to digital and to power the mic itself.
I currently use the Audio-Technica AT875R shotgun mic for my YouTube videos. Example here: https://www.youtube.com/watch?v=J-A7lezIIvo.
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I use the CAD e100s (new generation e100Sx just came out) for VO in my WhisperRoom booth.
I use the Focusrite Scarlett 2i2 preamp/interface for both. It works like a charm.
Let me know if you have any other questions!
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John