How to buy Poloniex?

Could you please explain the steps to buying Poloniex in a simple and concise manner? I'm a bit new to the world of cryptocurrency and would appreciate some guidance on the process. What do I need to do first? Do I need to set up an account or provide any personal information? And once I'm set up, how do I actually make a purchase? Are there any fees involved, and if so, how much are they? Lastly, are there any security measures I should be aware of to protect my investments? Thank you for your help!