You must be running a version of Microsoft windows, a Mac operating system or Linux/Unix. Both programs are Java programs and so you must have a Java Runtime Environment (JRE). The programs require version 1.6 or later. If your computer is fairly new, you probably have an appropriate JRE. If you're not sure, search for a folder named Java on your computer.
MathpadDraw is somewhat of a memory hog; it requires 256mb of memory. Furthermore, a fast processor is needed or some of the drawings will be unbearably slow.
When you click on one of the links below, the desired program is downloaded. Probably you'll want to save this download somewhere, say your desktop.
Windows and Mac users - After the download, a double click on the file will install the program.
Linux - The download is a shell script. Run this script and the program will be installed. (If necessary, change the permission mode of the script file to include execute permission.)