Before downloading it is always a good practice to make a ZT1-Downloads folder somewhere on your system, such as in your desktop or "My Documents" folder so you can find it easily. Save all the files you download to this folder. If you are using Internet Explorer, before downloading a file from a web site, you should move the pointer over the download link and look at the bottom of the browser to see the name of the file. If it shows that the name of the file ends with .ztd, Internet Explorer might not use the correct name for downloading, in which case you will have to change the name to end with ".ztd", either within the download window or after downloading. But most sites' files are in zip files that have to be unzipped using an unzipping program before a download can be installed. For unzipping files, many people use Winzip or Winrar, which are commercial programs. If you are using Windows XP or a newer version of MS Windows, you can use a built-in unzipping program by right-clicking on the zip file and clicking "Extract All". A very flexible unzipping program is 7-zip, a free and open source program, that can be found at: http://www.7-zip.org
It is often easier to work with files on your computer if you can see file extensions. Sometimes your system is set to not show file extensions by default. To change this in Windows XP so you can see the .zip or .ztd file extension, do the following. Open windows explorer or My Computer. Then click Tools in the menu and click "Folder Options". In the new window, click on the View tab. Scroll down to "Hide extensions for known file types" and make sure there is no check mark in the box beside it. If there is a check mark in the box, then click it to uncheck the box. Click OK and close the window to return to explorer. You will now be able to go back to windows explorer and see the .zip & .ztd file extensions.
If you need to rename a file you downloaded, such as if you downloaded a ".ztd" but Internet Explorer renamed it to something else, then right-click on the downloaded file and click Rename. At the end of the file name, you can delete the extension after the "." and put in a different extension. If you do change an extension, you will be asked if you want to continue.
When you are ready to install the files you have downloaded, unzip the files to the folder you are using for ZT downloads and then manually copy them to the locations listed below. Do Not use the ingame "Check Locally" feature. This adds extra unnecessary files that are difficult to locate when you want to uninstall the download.
After unzipping the zip file, use copy & paste to place the files as follows
Animals and Scenery Objects
.ztd files
C:\Program Files\Microsoft Games\Zoo Tycoon\dlupdate (if you have a dlupdate folder)
C:\Program Files\Microsoft Games\Zoo Tycoon\Updates (if you do not have a dlupdate folder)
Buildings
.ztd files
C:\Program Files\Microsoft Games\Zoo Tycoon\dlupdate (if you have a dlupdate folder)
C:\Program Files\Microsoft Games\Zoo Tycoon\Updates (if you do not have a dlupdate folder)
.dll files (lang)
C:\Program Files\Microsoft Games\Zoo Tycoon
Scenarios
.ztd files
C:\Program Files\Microsoft Games\Zoo Tycoon\dlupdate (if you have a dlupdate folder)
C:\Program Files\Microsoft Games\Zoo Tycoon\Updates (if you do not have a dlupdate folder)
.dll files (lang)
C:\Program Files\Microsoft Games\Zoo Tycoon
.zoo files
C:\Program Files\Microsoft Games\Zoo Tycoon\Maps
Zoos & Workbench Maps
.zoo files
C:\Program Files\Microsoft Games\Zoo Tycoon\Saved Games
note: you can actually open these files from anywhere as long as you navigate there when loading the saved game
NOTE - "C:" noted above is the default drive path; if you have installed ZT to a drive other than the default drive, then please use that path (D: E: etc)