<p>What language will be used in your introductory programming sequence? You could get a compiler and IDE for that language, and start writing programs in that language. There’s nothing for writing programs, other than writing programs.</p>
<p>Web scripting isn’t going to be much help, particularly if you’re talking about markup languages.</p>
<p>You’ll probably be using C++ or Java, depending on where you go. It shouldn’t be hard to start writing programs in these languages in fairly short order. I’ll take it upon myself to help you get all the (free) software you’ll need and even recommend some reading / exercises.</p>
<p>As far as the math/theory goes… I would recommend getting good with logic, proofs, and some basic counting techniques and graph theory. I can do the same for this as for the programming.</p>
<p>Good luck!</p>