Contacts and calendar events are designed to be synced with a supported application on your computer with iTunes serving as the sync conduit.
If you aren't syncing contacts and calendar events with a supported application on your computer via the iTunes sync process and you aren't accessing an email account that provides over the air syncing for contacts and calendar events, your only other option is transferring your iPhone's backup to your iPad.
When you sync your iPhone, open it in iTunes and choose information. Your contacts will be there. Tell iTunes where you want to sync your contacts. The options are Google, Yahoo and Windows. Once you've synced to one of those locations, connect your iPad and after sync, do the same, only this time tell it where to sync contacts from.
Another solution that is a wonderful option is to buy MobileMe from Apple. It's a cloud service that syncs calendars and contacts between all your devices. With MobileMe, when you update a contact on your iPhone, it will automatically update on your iPad and vice-versa. Plus it syncs all your calendars as well.