A lot of times, users tend to just walk over to a technician and tell them that they need help with something. This is an informal request and has to be logged into your service desk just like any other request so that it gets recorded properly. But since it has been reported personally, it has to be done manually by the agent.
To do this, you will have to fill out the ticket form on behalf of the requester from the agent portal. Since you will be doing it as a technician, your form might look a bit different from what your requester gets to see. You might come across some more advanced fields that will help you in categorization and incident management.
Quick guide for agents to log in requests through your portal:
Login to your service desk as an agent.
Click the New button.
Choose between Incident / Service Request based on the category of the ticket.
Enter the description and mention any details about the issue.
Use the ticket fields to fill out any additional information
Make sure you change the status of the ticket to Open (if you need to work on it), Pending (if you are waiting on something) or Resolved (if the issue has been fixed).
Click on the Submit button to create a ticket.
Additionally, if you want take up the ticket and work on it yourself, you will have to assign it to yourself from the ticket properties section.