You can search the Backend of TYPO3 easily by using the Edit/Search field.
This tool can be used to locate particular pages (just where is page id #234?), to find a user (was Kelly Jones' UserName kx34333d or ???), or any page containing a word, phrase, or number/s.
Search String: Your search key word/s
Levels: How deep in the Page Tree you want to search.
Show Records: You can limit the number of records that are displayed in each Record Type. This can be helpful if you're looking for particular page, but using a term that might generate an abundance of results in a category such as Website Users.