How do I deposit USD in Huobi?

As a cryptocurrency enthusiast, I'm curious about the process of depositing USD into Huobi, a leading digital asset exchange. Could you please elaborate on the steps involved? I'd like to know if there are any specific requirements or restrictions I should be aware of before initiating the deposit. Additionally, I'm interested in understanding the time frame for the deposit to reflect in my Huobi account and if there are any associated fees. Your guidance in this matter would be greatly appreciated.