Hi Sara,
RHN=Right Hand Needle
Glad you found the forum, and we're happy to have you here.
I'd love to help you out, but I'm a little confused by what you mean by "changing the yarn color to make a multi colored fabric." Are you asking how to work with more than one color of yarn at a time, or are you perhaps wondering about using a multicolored (variegated) yarn instead?
If you can tell me which one you are curious about, I'll do my best to answer your question.