I'm 18 and very new to music theory. I was in band and middle school for a year and took Music Appreciation in my senior year of high school. But one thing I never came to understand was sound keys etc. I like to write music a lot, but I'm not the best singer. I often listen to instrumentals and get inspired to create a song off of them. My question is, is it necessary or better for your voice to match the music? Cause I'm listening to one instrumental right now and I wanna make a song to it but I'm not sure if my voice or voice settings need to be in the same key as the instrumental.
Imagine someone has written a song for you to sing, and you're a good singer. You get half way through, and you're straining to hit the high notes in that part. So much so that you sound awful, but the rest of the song works well.
What should happen? Your voice won't go any higher - it sounds like a strangled parrot when you try. The solution is to lower the key of said song, so that those too-high notes drop down into your range.
Provided that action doesn't take the low notes in the song right down into your boots, the whole song becomes successful.