Whenever you set up an e-mail account, with a client such as Outlook Express, you have to provide internet 'addresses' for the servers which accept the mail you want to send or receive the mail which is sent to you. These are usually something like pop.myisp.com and smtp.myisp.com.
The information you require should be on the website of your e-mail service. (That's probably, but not necessarily, your Internet Service Provider).
If that still doesn't make sense to you, please post a response stating:
a) the name of your e-mail provider (e.g. AOL, Tesco, beeb.net, claranet, Gmail, Yahoo, or whatever) ; and
b) the method you're using to send the pictures. (i.e. Are you directly using an e-mail client, such as Outlook Express, or are you sending the images by using an option within an image-viewing program).
Chris