Not at all trying to discourage you, but a lot of the early days of music production is just slowly learning. a program like Reaper which is a full DAW (digital audio workstation) is as complex as photoshop, or video editing software... there are simply so many different features and stages to audio production that it takes a long time to get your head around the basics of it.
i'll try to give you a quick basic run down of some of the technology, maybe if there are any parts you need further help with you can DM me or something?
first of all what i meant by "audio interface", is a device that handles the audio separate to your computer, that lets you plug things into it (like a microphone) to record them and also you can plug in speakers, headphones.
the reason we use audio interfaces is because they are separate to your computer you get far less lag in the audio when recording if you use an interface, the inputs are also invaluable obviously.
so the mpc Ren is different to most audio interfaces, because it's also a midi controller. a midi controller means a device that sends note values to a computer or synthesizer (midi devices don't make sound on their own). to complicate things further, it's not just a hybrid midi/audio device, it also works with it's own software in a unique way for it's beat making/chopping/sequencing capabilities.
when you're just recording vocals in reaper, you don't need any of that beat making stuff, you just want to use the mpc ren as an audio device working directly with Reaper. this means that the pads, all the controls, the screen on the ren are effectively NOT working with Reaper (those controls are meant for mpc software control, not to do with the audio interface) you're only using the Ren as an Audio Interface - basically all the ports in the back of the ren for microphones or other input cables get sent directly to Reaper for you to record through one of them.
you can follow a guide here:
https://www.youtube.com/watch?v=gtTshPV4bpk for basic recording in reaper. where he is setting up the audio device, you should select ASIO as the device type and Ren as the driver. make sure the input for the track you are recording onto is set to the same as the one your microphone is plugged into, you will know it is correct if you see the levels bouncing up as you test the microphone by speaking into it or tapping it.
if you're just recording the vocals in Reaper, you would want to get your beat out of the mpc software as an audio mixdown. follow the instructions in the manual first to lay out the order of your sequences using Song Mode within the MPC Software, then go File > Export > Audio Mixdown or just press Ctrl + Shift + E. This will give you one .wav file that you can drag and drop into reaper for the beat underneath your vocals, or if you choose separate outputs you will get one file for every track in your beat, so you can adjust the levels later (unlike the single .wav which you cannot edit the volume of, eg. if the drums are too quiet after you add vocals you can't make the drums louder without making everything else louder too)
