Starting off you will first have to make a Gmail account. Simply go to google.com and make a new account from there.
After that, on the top bar menu, there is a "Calendar" button, select that to begin.
Once on follow the short tutorial, and if necessary, go back into settings to mess around with what will fit with your life. For example, if you enter in a time to head to a dinner, how long before you get an alert saying that you have a dinner.
Now, simply click the settings tab, but this time select the "sync with mobile device" and a new tab should appear.
Either choose the iOS device ( includes iPad, iPod touch ) or the android link.
Finally, follow those simple instructions and you should be good to go.