jaginc,
You
have to have Java installed if you want to install mrpostman as it programmed 100% in Java, are you sure you have Java installed on your system?
To check go to Control Panel and see is "Java Plug-in" is there, if it is, open it up click on the "update" tab and from there click on "get java update", if your java is out of date it will give you the option to download the latest one, do so and install it.
After this download "mrpostman" from
HERE to your desktop.
When it is downloaded double click the file and run though the installation.
Hope this helps

--lee