Can anyone give me advise as a male on how to start singing high pitched

Context: I’m 15 and just started gigging with my brother (I play drums) and we play lots of oasis and arctic monkeys songs. Since it’s only the two of us we thought thought I could start singing backing vocals for our songs. This means I need to sing really high pitched so I sound like Matt heldars or Noel Gallagher and do harmonies in songs like cast no shadow and stand by me The only problem is I have no singing experience whatsoever and just sound like I’m talking but all the words are long Any advise no matter how simple is welcome Thanks 🙏