If you didn’t set up Windows Live ID during phone set up on first start or you may want to set up more than one Windows Live IDs, then you can do this by following the steps given below.
To make set up of Windows Live Account in Windows Mobile you have to get connect your device with Wi-Fi or through cellular data service of your carrier. You may also be interested to know that how to connect to WiFi on Windows Phone 7 or how to Share PC internet / Mac internet with mobile devices.
Set up Windows Live Account on Windows Phone 7
When you first time set up your Windows Phone that asks to sign in with Windows Live ID but if you did not perform those steps at that time or have more than one Windows Live IDs then follow the steps below to set up primary Windows Live ID or additional Windows Live ID on Windows Phone.
On Windows Phone 7 home screen tap the “Arrow”.
Tap on “Settings” and then tap “Email & accounts”.
Tap “Add an account” > “Windows Live”.
The “Before you sign in” screen will appear if you did not provide Windows Live ID during Windows Phone start set up, so tap “Next” .
Tap “Windows Live ID” box and type your Windows Live ID then tap on “Password” box and enter your Windows Live password. Then tap on “Sign in” button
All is done, now your Windows Live email, contacts, calendar, photos, and all of the other stuff will be synced to your Windows phone.