Most websites created by Thisonly use 1&1 servers. If so and unless instructed otherwise, go to 'Tools' then 'Accounts' then 'Add' and choose 'New'. Then follow the usual steps for setting up an email account using these details (might help to print this first):

Email address:	you@whateveryouraddressis.com
Password:	I'll send this to you
Incoming mail (POP 3):	pop.1and1.co.uk
Outgoing mail (SMTP):	auth.smtp.1and1.co.uk

Tick the boxes for 'remember password' and 'my server requires authentification'.