Downloading and Installing App Inventor
In order to use the App Inventor you will need to download it to your computer. There are some minimum system requirements that you need to be aware of. Microsoft Windows, Apple Macintosh and Linux/GNU operating systems can be used, although note that older Apples using PowerPC processors cannot run the tool. As long as your computer is running Windows XP, Windows Vista, Windows 7, Mac OS X 10.5 or later or a Linux Ubuntu 8 or later or Debian 5 or a later version, then you should be fine to install App Inventor.
You will also need to make sure that your browser is up to date, so make sure you have Mozilla Firefox 3.6, Apple Safari 5.0, Google Chrome 4.0 or Microsoft Internet Explorer 7 or later versions installed.
Finally, ensure that the Java is installed on your computer. Head to check http://www.java.com/en/download/testjava.jsp and if the result is negative follow the instructions there to install the most up-to-date version.
To install on Windows, visit http://dl.google.com/dl/appinventor/installers/windows/appinventor_setup_installer_v_1_2.exe, and once the file is downloaded run it to begin installation. Note that you should not change the installation directory.
Mac users should download the file from http://dl.google.com/appinventor/installers/mac/AppInventor_Setup_v_1.1.dmg. Once the download has completed, double click the AppInventorSetup.pkg file to begin installation and follow the instructions.
For installing App Inventor on Linux Debian distros, head to http://dl.google.com/dl/appinventor/installers/linux/appinventor-setup_1.1_all.deb and use your usual package installer to install. The software will be installed in /usr/google/appinventor-setup.
Note that you will need to connect your Android phone to your computer in order to use App Inventor successfully. Depending on your phone and which version of App Inventor you are using, this may require some additional research on your part.