In the File Search tab, enter the text to search for in the Containing text combobox. It keeps a record of texts entered during this session, so you can pick a previous search text.
By default, the search uses simple glob-style wildcards. To use full regular expressions and control case sensitivity, select the appropriate checkboxes.
Use the File name patterns combobox to restrict the names of the files that are searched from. For example, if your scripting language is Python, set the pattern to be *.py to only search from Python files.
The dialog has some other more advanced settings, and can even be used to replace the matching text across files, but these features are not covered here.
Click the Search button to perform the search and to show the results in the Search view, which appears in the current perspective. It displays a tree view of the files searched and the line numbers within them where the search text matched.