Move the contents of every folder in the .rar to the folder of your The Ship directory with the same name. If the folder does not yet exist, create it first.

An example: C:\Half-Life\Steam\SteamApps\duke@bubblegum.com\the ship\ship

Unzipping/unrarring into your The Ship directory may also work but I can not guarantee it will add the content to the folders or entirely replace the folders instead! Do it with caution!