I have no Wifi connection anywhere near my place. I'm not able to download the Black update because of this. Please could someone tell me how to update the phone without a Wifi connection?
Windows Phone has an Over-the-Air download size limit of 50 Mb. It applies for the Windows Phone Store for sure, but apparently also for updates.
Someone asked a similar question in this Microsoft Community thread, and as you can see in the replies, you need Wifi.
If there's really no place where you can get Wifi nearby (cafe, fast-food, airport, other public place...), try asking a friend to set a wifi hotspot with is phone.