Hi

I am a little confused as I cannot work out the difference between Sen guzelsin and siz guzelsiniz. Does Siz guzelsiniz mean speaking to more than one person? I am very new at this!

Hayley

Yep Hayley, exactly right. Siz is more than one person. Check out the Personal pronouns section on this site.
http://www.turkishclass.com/basic_pronouns.htm

Ah thanx a lot. I will do

Siz is both singular and plural

Yes but when it's meant to be singular then it is a polite way of addressing someone.