Here is a whole "course" devoted to the task of creating an email signature in Microsoft Outlook 2010. On this page, just click "start this course". These options are very snazzy and comprehensive. But, there's that "ribbon-reference" again.
IF you don't have a half hour to devote to the task, here are the step by step directions.
And here is a one minute video that sums up the process.
And, for the final frustration. I've heard from folks that they create a signature in outlook, but then it doesn't show up in web-based. My fundamental understanding of this is that you have to go through the same process twice. In both outlook express (on your computer in school) and in web-based Microsoft Outlook Email. If that understanding is incorrect, please address a "fix" in the comments section.