Help with API's please!

Hello all,

I am trying to work with a api I have gotten from this site (http://www.wunderground.com/weather/api/)

The problem is I have no idea what I am doing and can't find any valid information online that really helps out.
I am trying to work the weather into my Windows Form... I have found a way to pull the data into a rich text box, but I don't understand how to pull the information from it.

Okay so when I pull the data I have it going to a richtextbox and the contents are

{
"response": {
"version": "0.1",
"termsofService": "http://www.wunderground.com/weather/api/d/terms.html",
"features": {
"conditions": 1
}
},
"current_observation": {
"image": {
"url": "http://icons-ak.wxug.com/graphics/wu2/logo_130x80.png",
"title": "Weather Underground",
"link": "http://www.wunderground.com"
},
"display_location": {
"full": "San Francisco, CA",
"city": "San Francisco",

How exactly would I have for example Label1.text equal the value of "full": ...? Meaning that Label1.text = "San Francisco"?