Adding a new External Link

The workflow:

Using External Links » External Links click on Title to get the list of links sorted alphabetically.
Scroll through the list and find the External Link Term that is going to be used for the new entry.
Of the entries grouped by that particular link term, decide where you want the new entry to go an pick a number half-way between the numbers used for those two entries, e.g., if the entry should appear between MAYA (000400) and The Patriarchal Order of the Holy Cross of Jerusalem (000500), then the number for the entry is 000450.
Using External Links » Add New set the title to the number, a colon, and a brief descriptive title, e.g., 000450: Vocations
Set the External Link Term
Fill-in the content with the markup you want to appear on the External Links page.
If there is a publication date, set that.
Finally, Publish