You can install Eclipse on your computer in order to work on assignments and labs.
First, get the Java Development Kit (JDK):
Click on the Download JDK button. Once the download has completed, install the JDK. (On Windows, the installer is an executable file which you can run.)
Then, download Eclipse:
Get the "Eclipse IDE for Java Developers". The download is an archive file. Just extract it somewhere, and run the eclipse.exe executable to start Eclipse.