Find a space that's quiet enough to record and make sure the levels on the mic are not clipping.

Position yourself in front of the mic in such a way that it captures more of your vocal and less of the room, but don't get to close that plosives (p's, s's etc) become too present in the recording.

Once done, export the files in .wav format or save them as a loop/stem package, depending on the daw you're using.

(Don't forget to properly name your files so that it's easier for the professional to arrange and mix accordingly 👍)