Besides entering contacts, you can:
Use your iCloud contacts: Go to Settings > iCloud, then turn on Contacts.
Import your Facebook Friends: Go to Settings > Facebook, then turn on Contacts in the “Allow These Apps to Use Your Accounts” list. This creates a Facebook group in Contacts.
Use your Google contacts: Go to Settings > Mail, Contacts, Calendars, tap your Google account, then turn on Contacts.
Access a Microsoft Exchange Global Address List: Go to Settings > Mail, Contacts, Calendars, tap your Exchange account, then turn on Contacts.
Set up an LDAP or CardDAV account to access business or school directories: Go to Settings > Mail, Contacts, Calendars > Add Account > Other. Tap Add LDAP account or Add CardDAV account, then enter the account information.
Sync contacts from your computer: In iTunes on your computer, turn on contact syncing in the device info pane. For information, see iTunes Help.
Import contacts from a SIM card (GSM): Go to Settings > Mail, Contacts, Calendars > Import SIM Contacts.
Import contacts from a vCard: Tap a .vcf attachment in an email or message.
Search a directory. Tap Groups, tap the GAL, CardDAV, or LDAP directory you want to search, then enter your search. To save a person’s info to your contacts, tap Add Contact.
Show or hide a group. Tap Groups, then select the groups you want to see. This button appears only if you have more than one source of contacts.
Update your contacts using Twitter, Facebook, and Sina Weibo. Go to Settings > Twitter, Settings > Facebook, or Settings > Sina Weibo, then tap Update Contacts. This updates contact photos and social media account names in Contacts.