To download/install Office 365, swipe up from the start/metro screen. You should see the programs in alphabetical order. The Office 365 icon is under M for Microsoft. If you tap on it you should be prompted to enter your Microsoft account login username/password to begin the download. The cloud based subscription should be free for the first year. You should be able to log into your account on another computer as well. To create a Microsoft account go to: https://signup.live.com
For all Windows 10 devices, your device has pre-installed apps called Office Mobile. If you do not see your office mobile icons on your device you will need to download them from the app store on your device.