Well, that's not that hard to do. What you want to do is add a Timer to your form and set it's Interval to 1000 ms (equals 1 sec).
(An article on Timer's can be found here: Pre-beginner's guide to using a timer
Then, when it ticks, you start up a BackgroundWorker and tell it to do what you want. I suggest looking up BackgroundWorker on google, or in the articles here. A good start might be:
BackgroundWorker Threads and Supporting Cancel
Beginners Guide To Threading In .NET Part 5 of n
The BackgroundWorker is a bit much to get into in a quick answer, but there is a ton of information available on the web.