How do I buy Bitcoin with USD?

Could you please elaborate on the process of purchasing Bitcoin with USD? I'm new to the world of cryptocurrency and finance, and I'm seeking guidance on how to make this transaction securely. Could you walk me through the steps involved, including setting up a wallet, finding a reputable exchange, and completing the purchase? Also, are there any fees or taxes I should be aware of? Additionally, I'd like to understand the risks involved and how to mitigate them. Your expertise in this field would be greatly appreciated.