; Set the name and version of the installer
Name "MyInstaller"
OutFile "MyInstaller.exe"
InstallDir "$PROGRAMFILES\MyProgram"
InstallDirRegKey HKLM "Software\MyProgram" "InstallDir"

; Set the default installation options
RequestExecutionLevel admin
AllowSkipFiles off
AllowRootDirInstall off

; Create the components and sections for the installer
Section "Main Program" SEC_MAIN
    SetOutPath "$INSTDIR"
    File "MyProgram.exe"
    File "README.txt"
SectionEnd

Section "Optional Files" SEC_OPTIONAL
    SetOutPath "$INSTDIR\Optional"
    File "OptionalFile1.txt"
    File "OptionalFile2.txt"
SectionEnd

; Add the installer pages and controls
Page components
Page directory
Page instfiles

; Define the installation finish page
LangString FINISH_TEXT ${LANG_ENGLISH} "Installation complete! Click Finish to exit."
LangString FINISH_SUBTEXT ${LANG_ENGLISH} "Thank you for installing MyProgram."
!insertmacro MUI_FINISHPAGE_SHOW README $FINISH_TEXT $FINISH_SUBTEXT

; Create the uninstaller for the installer
Section "Uninstall"
    SetOutPath "$INSTDIR"
    Delete "$INSTDIR\MyProgram.exe"
    Delete "$INSTDIR\README.txt"
    RMDir "$INSTDIR\Optional"
    RMDir "$INSTDIR"
SectionEnd
This code creates an installer for a program called "MyProgram", with two components: the main program and some optional files. The installer creates a shortcut in the user's start menu and an entry in the add/remove programs list. It also creates an uninstaller for the program.