Step 1: With 7Zip installed, double-click the update file. An archive/folder will open.
Step 2: Within that archive are files like "d12_images.rpa" and "laptop_images.rpa" - you want to highlight all the files within this archive and drag/drop them into your Stranded in Space "game" folder - overwriting everything that wants to be overwritten.
Step 3: If there is a file within your "game" folder called exactly "scripts.rpa" - make sure to delete it. It has to be exactly called that - if there isn't a file exactly called that, you don't need to delete anything.