To start using ChatGPT, just go to https://chat.openai.com/auth/login and create an account (you can use email, Microsoft account, Google account, or Apple account).
Once you have an account and verify your email, you can log in and begin prompting.
At the first login, ChatGPT provided some tips. Notice that it says it may give you inaccurate information.
The free version of ChatGPT is 3.5. For a monthly fee, you can upgrade to 4 which has additional functionality.
The information in ChatGPT 3.5 was updated in January 2022, from information it trained on in 2021. So not all of the information is up to date. Some of the other AI tools do use more up-to-date information.
Example of how ChatGPT can help with brainstorming.
This is a tool that can also help you organize your time and workload.