JTides is a Java program. This has many advantages, such as the fact that it can run on nearly any computer, but there is one special requirement -- JTides must have access to a current Java runtime engine. The Java engine that was supplied with Windows is unfortunately out of date (and Microsoft is no longer supplying any Java engine at all).
The correct Java runtime engine is available at http://java.sun.com/j2se/1.3/jre/. This isn't a link, unfortunately (because this isn't really a Web browser). You need to copy the blue characters into a Web browser to visit the site. Presumably, since you are reading this, you have already installed this engine.
If you own an Apple Macintosh computer, you do not need to download the above runtime engine. If you have an OS version before OS X, there unfortunately isn't one for your computer, but if you have OS X (the newer Macintosh operating system), the correct Java runtime engine is already installed on your computer.
Because you have installed the Java Runtime engine, the JTides executable file will be associated with the Java engine and can be run by simply clicking it. This means shortcuts can be easily made in Windows, and placed wherever they are needed. The Windows installation package creates a shortcut for you, located in the JTides program group.
Caution: Do not install JTides in a directory path that has spaces in it. This will prevent the program from running. The install program provided for Windows system owners chooses a path without spaces, but if you decide to move JTides.jar to a different directory, it will run there just fine -- unless there are spaces in the path.