How to add custom fields in the detail of a service request?

hello,

We want to expose the Department Name the Position Name and the serial number of the main point of contact of the service request as a field, in the detail of a service request (see picture)

Can you send us a documentation explaining, step by step, what to do?

It would be very important for us

Thanks

Gianfranco

On this page that a help desk agent can see , we would like to include the fields I mention above 

Thank you

Gianfranco