From the main menu, click Window > Preferences.

Select Help, make changes, then click OK.

Because Designer is built on Eclipse, you are able to use Help server functionality. It is a development tool for building your own tools. If you have a team environment where the entire team is using Eclipse, you might want to set up a common Help server, and then use that server for help files and content.

For more information on Help and the Help server:

(Optional) Expand Help, then click Content.

(Optional) Make changes concerning the Help server, then click OK.