The Umbraco content tree view allows you to navigate web pages through a logical site hierarchy. You can find a page by navigating through the tree itself if you know where the page is stored.
Alternatively a quicker approach might be to perform a search across everything in Umbraco.
Click the Magnifier icon in the upper right of the screen. Or hit CTRL + SPACE as a shortcut on your keyboard.
Using the search bar you can enter a search term and Umbraco will search for pages and media containing the term.