Outdorr lighting for taking pictures?

I have recently gotten into taking pictures, and followed along with my sister's photographer when she had her bridal pictures done. As the afternoon went on and it got darker, he used a flash that was mounted on a tripod and had an umbrella on it. I own a Nikon D7000, what equipment would I need to purchase to have this same set up?

You can use a nice Nikon SB700 with the mounting bracket that comes with it to mount it on a tripod. You can also find an attachment like the Lite Genius Lite-Scoop Flash Modifier which can simulate an umbrella in the bounce flash position (under $30). B&H Photo sells both items

Light stand
Umbrella mount/bracket for the light stand
Umbrella
If the flash you choose isn't capable of off camera communication with your camera you'll need triggers. If it is capable, then you are good to go and even better because it works i-ttl!

You have two choices:-

- a Nikon speedlight that will work wirelessly off camera in TTL (auto flash) or manual mode. This means the SB700 or the SB900. The flash power and triggering is controlled optically via the in camera menu. SB700 and SB900 flashes cost in the region of £280-£320. The advantage of this method is the TTL control (but this can get it wrong sometimes, like most things on Auto). The disadvantages are the high cost & the sometimes unreliable optical triggering (especially outdoors)

- a cheaper manual flash. You dial the flash output manually on the back of the flash (no TTL or in camera control).It is fired off camera using radio triggers. The advantages of this system are more consistent results, better triggering (radio vs optical) and they are MUCH cheaper - a YN560 flash costs around £40 and a set of radio triggers (RF602's for example) cost about £18. The disadvantage is no TTL & you have to walk over to the flash to adjust power rather than doing it 'in camera'.

Whichever flash system you choose, you will need a lightstand (about £15 from eBay), and umbrella to hotshoe adapter;
http://www.warehouseexpress.com/search/?q=umbrella%20hotshoe%20adapter

and umbrella. Umbrellas come in different sizes and can be shoot thru (white translucent) or reflective (black/silver). Prices vary from around £18 & up.

The Strobist blog is the best online resource for off camera lighting techniques - have a look at the video part way down the page - tells you everything you need & how to put it together;
http://strobist.blogspot.com/2006/03/lighting-101.html