Change text content of subscribe & welcome email

Hi all,
Please excuse my ignorance as im a newbie to this plugin and wordpress in general. i am however trying to learn!
My reason for posting is im trying to change the text, the content of the auto generated emails that the subscriber gets sent when he/she subscribes to the newsletter. The emails that are generated work fine apart from the ‘click here’ link when confirming the subscription so if anyone can help with that also id be more than pleased. i guess im asking where the file is that holds the email text content that i can access and tweak.
This has probably been asked before but unless i can understand it, its of no use..