To mine Bitcoin with an RTX 4090, you would typically use a mining software like NiceHash or MinerGate. However, mining Bitcoin directly with a GPU is not efficient due to the high difficulty of the network. Bitcoin mining is mostly done with ASIC (Application-Specific Integrated Circuit) miners, which are much faster and more efficient than GPUs.

Mining one Bitcoin with a GPU would take an impractically long time, as the network difficulty increases over time. It's more common to mine altcoins (like Ethereum) and then convert them to Bitcoin.

For a beginner, consider joining a mining pool, where you can combine your hash power with others to increase the chances of earning Bitcoin more consistently.