If you options are to buy a book all the way to re-enrolling in college, you may want to take a step back, as has been suggested. It's not that you can't do it, or shouldn't do it, but there are some major caveats with website design and implementation.
Do they have any of their own Analysts or Administrators? Talk to them, get their opinion. If it's just page update, I'm sure you could work from a template that's already there. You just have to understand how to safely do the updates...something the Administrator(s) can help you do.
When I teach my students, before a course during the initial introduction to that course I give them three rules to live by:
1. Data is King. Know, it love, back it up. It's the most important thing in your live...even over your family (I usually joke you can always make another family, but you can't get data back when it's gone).
2. RTFM. Self-Explanatory.
3. Murphy's Law: Anything that can go wrong, will...on the day the CEO is watching. Prepare...see rule #4.
4. 7 P's: Proper Previous Planning Prevents P*ss Poor Performance.
5. When in Doubt: Do Nothing Unless You 100% Know the Outcome OR click Next, Continue, OK, or any selection that makes you life go forward, as long as it does not contravene any of the previous 4 rules.
Rules to live by in the IT world.
All of these are applied in descending order of precedence.