There are two ways of picking a Chinese name. 1) Translate your English name. Yours, like people above are saying, would be something like 沙麗娜 or 娜娜. There are fairly natural names in Chinese, you are lucky. Usually when you choose a Chinese name like this, it sounds weird. My name, for example, you can't really translate to 勞倫斯 cause it sounds stupid.
2) You can pick a more authentic name, either based on your English name or completely unrelated - get a Chinese person to pick one for you. My Chinese surname 何 comes from my English surname, and my other two characters 安 and 傑 come from my middle names - Andrew and James. But you can pick a completely different name, my friend Sam is called 羅斌 which is completely unrelated.
Laurence