Please can someone talk me very slowly through doing a mail merge for address labels for Christmas cards?

[cleanandclothed]

I would like to take source data from excel and then print labels. How do I format the data I want to merge? Does it matter if some addresses have extra lines (eg a town and a county) and some don't?

Have a look through this Microsoft article and see if that helps:support.microsoft.com/kb/294684