How to buy US dollars on Binance?

As a cryptocurrency enthusiast, I'm often looking for ways to diversify my holdings. So, the question I have is: How do I effectively buy US dollars on Binance? I understand that Binance is a leading cryptocurrency exchange, but I'm not entirely sure how the process works for fiat currencies like the USD. Could you walk me through the steps? Are there any specific requirements or limitations I should be aware of? Also, are there any fees associated with buying USD on Binance? And lastly, is the process secure and reliable? Your insights would be greatly appreciated.