Making a script pack is easy. Just put all the files into a zip file, and change the extension to plsc
As for making windows, that won't be as easy. My first recommendation is to download the
interface tester. Then start looking at how other scripts are made with their windows. Start by looking at the less complex ones, find out how they work.
Personally, I use Visual Studio to edit my interface windows. It reads the interface schema file, and allows you to use the wonderful intellisense feature. It will even show you the schema in a very useful, graphical way.