Formal:
* Goeie dag, my naam is David. (Good day, my name is David.)
* Hallo, my naam is David. (Hello, my name is David.)
Informal:
* Hallo, ek is David. (Hello, I am David.)
* Hi, ek is David. (Hi, I am David.)
You can also simply say:
* David. (David.) This is a very common way to introduce yourself, especially in informal settings.
Note: "Goeie dag" is a more formal greeting than "Hallo". You would typically use "Goeie dag" when addressing someone you don't know well or in a more formal setting.