To report a problem, just go to the problem homepage, choose what area your problem is in, look at the list of frequently posed problems to make sure your problem isn't a common one with a simple answer, then fill out the problem form. Unix problems are generally handled by Eric Aune, and Windows problems by Byron (please don't contact them directly - go to the website with all problems). However, if there is an extreme emergency (say the entire stat network goes down at 9pm), you can call the IT emergency services at x4989.
If you are off-campus, you would not be able to access the Problem Webpage without a VPN account. In this case, you can send your problem to problem@rice.edu. Since there is no form to fill, remember to write clearly the problem priority, interested parties, how you can be reached etc.