Checkbox

I cant seem to find a simple solution to this:

When the program loads up(.oninit) checks a condition, depending on that condition sets a checkbox as either on or off.

Any help is appreciated, thank you.

InstallOptions docs...you can see how to write in the ini...
For example:

WriteINIStr "INIPath" "Field_number_of_checkbox" "state" "0"

Or with Modern UI,
!insertmacro MUI_INSTALLOPTIONS_WRITE "INIFile.ini" ...

!insertmacro MUI_INSTALLOPTIONS_READ $Var "INIFile.ini" ...

Stu