MPLAB® X IDE provides two methods to find something in the file that is currently displayed in the editor.
The first method requires the least amount of effort. Highlight an existing piece of text (e.g., a variable name, function name, or any other text in your code). The editor will automatically highlight all the matches in the current source file in gold. Also, a gold bar will appear in the error stripe at the far right to indicate the relative position of all instances that have been found in the file. Clicking on a bar in the error stripe will take you to that instance of the highlighted item.
The second method is mostly used when you are searching for something that isn't presently visible to highlight. Select Edit > Find… from the main menu. This will display a bar at the bottom of the editor, containing a text box where you can type in your search term. All the matching terms will be highlighted in orange and a gold bar will appear in the error stripe at the relative position in the file of each instance that was found.