Judy - If you join Mudcat, the info they require from you is :-
First name
Last Name
a "Mudcat Name" (which can be anything not already in use). Some people use their real name, others make something up.
a Password, so you can log in or out as suits you.
and An e-mail address which is usually only used when someone loses their cookie and forgets their password. Joe will send your password via the e-mail you have given. The e-mail you give is not displayed anywhere on the forum.

There are boxes on the form for addresses and phone numbers, but they are not compulsory, so you shouldn't have any worries about private data. The people who run Mudcat don't sell e-mail addresses.

There is a section where people can post a profile of their interests or their professional work, but that is purely optional and many of us don't. In my case due to "couldn't be bothered" syndrome as much as anything else.

Come on in, the water's lovely...
Quack!
Geoff the Duck (real name, honest!)