You are not gonna learn how to fight by asking a question on the internet.
Follow these steps for success
1. Find a local boxing gym, MMA gym or Muay Thai gym near you and go to that gym.
2. Your first visit to that gym is to simply find out the cost to join and train and the training schedule
3. Apply yourself, so train in your own time to maximise results
4. Ask experienced fighters at your gym for advice
5. Always listen to your coach and never give up, even if your first few competition fights are losses, trust me, my first 10 fights were losses
Enjoy and train hard
Fists up, chin down, bob and weave. Give 'em hell.