First, update everything.
Start by going to the Store and updating all your default Microsoft apps. They should update automatically when you open the Store, but if not, click or tap the Update notice in the top right corner of the Store.
Second, swipe in the Charms bar and tap the Settings Charm (or just hit the Settings button on the top row of your Touch keyboard) and then click or tap the Change PC settings item. Scroll to the bottom of that list, tap Windows Update and then click or press Check for updates now.
One might assume that is enough to get you all up to date, but not so. To update the built in Office suite over on the desktop, you need to go to the classic Windows Update. The easiest way to get there is to right click in the bottom left corner of the Start screen or hit Win+x and then select the Control Panel from that menu.
– Some Tips for new Surface RT Users – Asa Dotzler
Sounds easy enough.