From a Home screen, touch and swipe up to display all apps.
Tap Contacts then tap a contact.
Tap the Edit icon (lower-right).
Edit any of the information (e.g. phone, address, email, etc.) then tap Save (in the upper-right).
Depending upon the account type, the options presented may vary.
To add a pause (a 2-second delay between numbers) or wait, tap *#, tap Pause (,) or Wait (;) then tap Save.
To change the type of a selection (e.g., Phone, Address, Date, etc.) tap More fields, then tap the Dropdown menu located directly beneath the selection then select the desired choice (e.g., Mobile, Work, Birthday, etc.).