The dialogs for finding text within the IDE involve use of the flashlight and the search window or the typing of the Keyboard command control F. The flashlight and search window involves the three icons with a flashlight in them and the box just to the right (that has the entry pdf in this case).
To find text you type the text string you are after in the search widow. In turn, clicking on the 
icon finds the first occurrence of what you want in the current file, while clicking on the icon 
finds the next occurrence in the current file. Finally, clicking on the icon 
finds all occurrences in a specified group of files as discussed below.
You can also access search and replace through the search menu or by typing the keyboard shortcuts control f or control r. That dialogue allows access to more options and will search for the text under the current placement of the cursor.