哈哈~你好！我在上网啊

你好！你好吗？你在干什么 ？ 我很好！我在学习英文（汉语）。

You should try to write it in Chinese but not Pinyin. 你应该试着用汉语说，而不是用拼音。

i think it would much better if u can put it into "Qǐngwèn nǐ zài zuò shénme? (請問你在做什麼)" which means "May I ask u what u are doing?" That sounds more polite to me. "Gànshénme (幹什麼)" sounds kind of rude. we use it only when talking to our friends and family.

中国人很少说“你好吗？”