你好 is often used in a dialogue where you address the listener. Here is a community, so it's better to use 大家好 which means (Hi, everyone) The subject is missing in the sentence 就想学习汉语, you can put it like this: 我想学习汉语。 Also, put a " ," instead of a " ;" to divide a sentence. ";" is rarely used in daily Chinese. Keep up your good work :)