How do I transfer money to Steam?

Can you walk me through the process of transferring money to Steam? I'm a bit confused about the steps and would like some clarity. Is there a specific method that I should use, or can I use a variety of options? Also, are there any fees associated with the transfer, and if so, how much are they? Additionally, how long does it typically take for the funds to appear in my Steam wallet after I initiate the transfer? I'd appreciate it if you could provide a detailed, step-by-step explanation.