Synchronizing two folders

[Tito Ciuro]

Hello,

I'm quite new to rsync, and after reading and checking some examples I 
still have a question regarding synchronization:

What arguments should I use if I want to synchronize two folders?

I need to make sure that after synchronization, contents on each side 
are the same. If I have new files in folder #2, these aren't copied to 
folder #1 after the process. It only passes files one way (folder #1 
--> folder #2)

Any ideas?

Thanks so much,

-- Tito