Add Jira header to JSD portal

[Sam]

Just to clarify, by "header" I mean the part of Jira that's shown in the attached image.

I'd like to add a section of the Jira header that will always direct someone to a specific Jira Service Desk portal. Ideally, I'd like the text that says "Request Jira Support" always take whoever clicks on it to the URL of the specific Service Desk portal. How would you recommend doing this?