There are a few different ways to use Google Input Tools. The most common way is to use the Chrome extension. To do this, first make sure you have the Chrome browser installed. Then, go to the Google Input Tools page and click on the "Chrome" extension. Once it's installed, you can use it by going to any text field and clicking on the Input Tools icon.
Another way to use Google Input Tools is through the web interface. To do this, go to the Google Input Tools page and click on the "Web" interface. Then, type in the text you want to transliterate and select the language you want to use.
You can also use Google Input Tools on your mobile device. To do this, go to the Google Input Tools page and click on the "Mobile" link. Then, follow the instructions on the page to install the app. Once it's installed, you can use it by going to any text field and tapping on the Input Tools icon.