Setup.exe is a common name for installation files on the Windows platform. They usually function as an installer that allows point-and-click installation of some target program. Occasionally, you may need to edit setup.exe files for various reasons. If you developed the software, you may have made a typo in the installation text and need to make a quick fix. These kinds of things can be easily done with a binary text editor.
Download a binary editor (see Resources).
Use the binary editor to open your target setup.exe file. Usually, you can do this by clicking the "File" >"Open" buttons in your editor. Binary editors are only capable of searching files for hexadecimal values and ASCII strings. This means that you probably won't be able to change the functionality of the program with just a binary editor. You can, however, easily change the text that appears in the program.
Use your editor to search for text. Replace it with anything you like. Save the file.