For Windows, I don't believe there's any change from CS4 to CS5 regarding this optional plug-in. If you already have it, just copy it over. If not, you can get the CS4 optional package and copy it. (http://www.adobe.com/support/downloads/detail.jsp?ftpID=4048)
Make sure to copy the 64 bit into the 64 bit app directory, and the 32 bit into the x86 directory. If it doesn't work, sorry :-P Idon't have a Windows machine at and to test it out. Yes, this will be included in the CS5 posting when it comes out. I'm trying to get info on the ETA for posting.
You need to download the files for the add-ons that include Picture Package. Then you need to extract everything and put all the files into the corresponding directories in your Photoshop installation folder. There's more than one file that needs to be placed in your installation folder. I don't remember everything, but I think photoshop/presets/layouts is one of the folders that needs to be copied to your installation directory. Just cut and paste everything from the files you download and extract.
Are you asking, "how do you open a zip archive and copy a file out"? Here's one way:
You can download the optional plug-ins for CS5 Windows here:
Once downloaded, unzip (extract) the PSCS5OptionalPlugins_Win_en_US.zip package.
Note: If you are using a 64-bit edition of Windows, then, by default, there are two editions of Photoshop installed on your computer: a 32-bit edition and a 64-bit edition.
The default location of the Plug-ins folder for the 32-bit edition is
C:/Program Files (x86)/Adobe/Adobe Photoshop CS5 or CS4/Plug-Ins.
The default location of the Plug-Ins folder for the 64-bit edition is
C:/Program Files/Adobe/Adobe Photoshop CS5 or CS4/Plug-Ins.
1. From the PSCS5OptionalPlugins_Win_en_US folder, copy
/Optional Plug-Ins/Win32/ContactSheetII.8li plug-in into the C:/Program Files (x86)/Adobe/Adobe Photoshop CS5/Automate folder (for both Contact Sheet II and Picture Package) and/or
/Optional Plug-Ins/Win64/ContactSheetll.8li plug-in into the C:/Program Files/Adobe/Adobe Photoshop CS5/Automate folders (for both Contact Sheet II and Picture Package).
2. From the PSCS5OptionalPlugins_Win_en_US folder, copy the /Presets/Layouts folder into the C:/Program Files (x86)/Adobe/Adobe Photoshop CS5/Presets folder and/or
C:/Program Files/Adobe/Adobe Photoshop CS5/Presets folder.
3. Restart Photoshop.