How to pay with bitcoins?

Could you elaborate on the process of paying with bitcoins? I'm interested in understanding the steps involved from initiating a transaction to its completion. Could you explain how to set up a Bitcoin wallet, how to fund it with bitcoins, and then how to proceed with making a payment? Also, are there any security considerations I should be aware of when using bitcoins for payments? Additionally, what are some common merchants or platforms that accept bitcoin payments, and how do I know if a particular merchant accepts bitcoins? Thank you for your assistance in clarifying this topic.