When you are new to the sport of surfing, you will do well to master the art of swimming before you get up on a board. It is a skill that will keep you afloat, even when you fall off the board or lose it when the wave overwhelms you.
Buy a used board to practice as new boards can be quite expensive. Learn how to swim out to the incoming wave on which you will surf. Make sure that you keep the board nearby. Learn how to balance on the board first when you are lying down on it. Every board will have a different balance point and you need to find it and mark it for future reference. You can then lie down on the board, perfectly balanced and paddle out to meet the wave on which you are going to surf. the nose of the board should not dig into the water when you are properly balanced, and if it does, move back a bit. Too much weight at the back of the board is also not the right way of being on the board. The board should lie naturally in the water, and help you to move easily to catch the wave.
Paddle out to the wave, using both hands alternately and not at the same time, as this can tire you out faster. Once you have learned how to lie down on the board and paddle, start getting into a sitting position and remain balanced while you are paddling. Standing up on the board will require you to practice for days or weeks. Put your hands on the side of the board and push yourself up, while you sweep the feet under you. Keep the feet apart as this can help you maintain a low center of gravity.
Keep your eyes to the front and go looking for your wave to start your surfing experience.