If your XO is running a Release from 2008 or later, there is a Help activity for it. If it is installed on your XO, it will appear in your Home view with a (?) icon. You can install this activity from Activities/Help-G1G1 or using Software update in the Sugar Control Panel.
You can read a version of the same manual at http://laptop.org/manual The updated version of this Getting Started Guide is included, and you can use the menu on the left side of the manual page to jump directly to it if you wish.
Getting started pages
There is a small set of pages at http://laptop.org/10.1.3/gettingstarted/ for OLPC software release 10.1.3.
Getting started for earlier releases
If your XO is running earlier software, such as 8.1 which is on the first deliveries of 2008 Give One, Get One laptops or "Ship.2" release that came with the 2007 Give One, Get One laptops, you should consider upgrading your XO to a later release. See What release am I running?.
You can read the earlier Getting Started Guide online. You can also download this as a collection to your XO (in English and and Spanish), or download as a PDF or download in MS Word format.