CRM to R/3 RFC Connection

Hi Guys.

I have just got a ECC 5.0 installed on my desktop and have got CRM on my laptop.

I would like to know as to how can i create a connection (either RFC), so the entries that i do in crm get reflected in r/3 and vise versa.

I am new in this field and any kind of documentation,advice would be much appreciated.