Support tickets is the most common use for help desks, but its not limited to that AND you can have multiple of them for different purposes, for example to collect feedback on specific content.
Add a help desk
Navigate to your Account > Contacts > Help Desks
Click on Add help desk at the top right corner, and give it a name.
Customize how it shows for your memberes, the default assignee (admin in charge!), knowledge base if any. Optionally, offer interactions with one of your Bots on the Knowledge base Bot.

Choose which sites you’d like the help desk to be available on.
Customize the ticket pipeline - with every help desk, there will be a pipeline associated to it, so you can keep track of tickets, follow up with enquiries, and update the status. On the stages section you define the statuses for your tickets depending on your work flow. The most common ones are Open, Hold, Pending, and Solved.
Collect specific info by using Flags. They will display as fields when someone submits an inquiry through your help desk.

Add triggers when someone submits a ticket. It’s at the top right!
Save changes at the bottom of the page!
You’ll notice the Pipeline has been created for you, matching the help desk name. You’ll find submitted tickets by clicking on View tickets at the top of the Pipeline page.