How to cash out OMG on Coinbase?

Could you please explain the process of cashing out OMG tokens on Coinbase in a step-by-step manner? I'm a bit new to cryptocurrency and I'm not sure how to go about it. Specifically, I'd like to know how to convert my OMG tokens into a fiat currency like USD and then withdraw it to my bank account. Is there a fee associated with this process? And what are the potential risks or limitations I should be aware of? I appreciate your help in clarifying this process for me.