The Google apps launcher is an icon that contains 9 small squares and can be found in the upper right hand corner of the google.com webpage. You can customize this menu by dragging and dropping your commonly used apps to the top of the list.
However, if you do not see an app in the list, simply click 'more' to find the app you want. If you still do not see the app in the more section, then you must go to that app, click on the apps launcher, and you will be prompt to add it as a shortcut to the list.
For example, Google groups do not appear in the apps list and it does not appear under the more section. I went to groups.google.com, clicked on the apps launcher, and a message appeared for me to add Groups as a shortcut, as shown below.
You can find more information about this topic at Google Support.