A used older desktop is a good starting machine. I think Unraid is a good starting point as the community is more welcome to completely new people needing a lot of help. Also this channel has a tone of good guides for Unraid: https://youtube.com/@SpaceinvaderOne?si=A8BWLbMq42KzHD8I
I suggest starting off cheap to learn. Then you can spend money as you determine what is necessary based on problems you encounter. One VERY important thing to remember is that HDDs fail, power surges kill motherboards, water leaks kill the whole thing. If you don't want to loose family photos, MAKE SURE YOU HAVE IT BACKED UP OFF YOUR SERVER. Preferably "off-site".