As an example, here is how the search definitions are laid out ...

To include or exclude the next line of search criteria you use the And/Or menu to set how each line interacts with the next.
If you are not using the next line of criteria, then leave the And/Or menu blank.

As an example, I want to search for all members with the word Love in their username and the word Lust in their email addresses ... here is how it would look ...

The results would list only members with Love in theirs usernames AND Lust in their email addresses

As another example, I want to search for all members with the word Love in their username but I want to exclude those with the word Lust in their email addresses ... here is how it would look ...

The results would list only members with Love in their usernames and those without Lust in their email addresses

As another example, I want to search for all members with the word Love in their username OR those with the word Lust in their email addresses ... here is how it would look ...