Don't Panic!
PLT Scheme has a variety of resources designed to help you with any problems you may have.
Help Desk
Your first stop should always be with the help system that's built into PLT Scheme and available from the DrScheme menu or by pressing F1 with the cursor on a search term. This documentation is customized for your installation, and may include documentation for optional packages you've installed. As a second line of defense, the documentation for the core of the most recent version of PLT Scheme is available from this web site.
Not sure what to search for? The documentation includes a guide (also located in your local copy of the documentation) that provides a narrative introduction to many of PLT Scheme's features.
Learning how to Program
Try going through How to Design Programs.
Searching the Web
The Scheme Cookbook is a wiki for Scheme snippets (though not a PLT-specific one). Additionally, your favorite search engine may well provide answers for many of your questions, particularly if you include "PLT" as a search term.
The Mailing List
The plt-scheme mailing list is a great source for answers to questions when the above resources don't pan out; sign up for it in the community area of the website.

Thanks for using PLT Scheme!