how to track visitors from 2 different web site + code in newsletter

how to track visitors from 2 different web site + code in newsletter

Hello 

Do we have to use the same code to insert for 2 different web site we own ? we only want to use tracking not "chat" at the moment

Another additionnal question : do we have to put any tracking code in newsletter we send or not to match visits and zoho CRM ? if yes, where to put the code ?

thanks 

nono