A newbie needs help. (Soil moisture sensor).

So, I'm working on a project where I want to use the Arduino soil moisture sensor to continously upload the values in percentages to a website. The problem is that I don't have a network shield for my Arduino (Uno) board. It will, however, be plugged into a PC with an internet connection.

So what I need is to take the values from the sensor, and through the PC get the values outside of the Arduino software and uploaded to a website for continuous streaming.

I would also like to have the PC send an e-mail (or other notification) to me when the values reach a certain point.

How would I go about doing this?

That would be a PC problem, not an Arduino problem. You will need to have a program running on the PC that reads the Arduino (i.e. a serial port) and sends the data wherever you like.