The first thing you need to do is to start paddling on your board in the direction that the wave is heading in. This is because you are looking to ride the wave, so you need to check how far it can take you. Once you feel the force of the wave starting to push you forward, you need to get ready to take it to the next step.
Place your hands on the board, just below the area where your shoulders are located at. This is essential, since it will prevent you from slipping and will help you transfer the most energy
Now push yourself upwards using your hands and pop up, while landing on your feet on the board.
When you have popped up, you need to place your left foot forward, or your right foot forward, based on which ever foot you generally lead with, while doing all day to day activities.
You need to remember one key rule, that based on how big your board is, you need to adjust the area that your feet will cover. If you have a smaller board, you will open your legs less, as compared to if you have a much bigger board.
The last thing you need to focus on, is that you need you need to go on and hit the beach as much as you can so that you get to practicing your craft of popping up on the board. Try doing it at variable paces till you get better.