How to modify a CCK Field variable to format it a specific way?

Hi,

I created a new CCK page where the user can enter in a tracking ID for either UPS or FEDEX in that field.

Now I created a views page listing all the created content, but the problem is that the tracking #'s aren't linked. How would I make these tracking # hotlinked once the user inputs the information? I am guessing it must have to do something with the PHP CODE box in the field edit settings. What do I need to put in there?

Thanks,
dux