Hi, When a user registers on our site for the forum they are getting a welcome email to set their password but I don't know where this email is or how to modify it. Can you help?
The registration/login/password part is handled by Wordpress not wpForo.
What you look for probably is in Wordpress language files or templates. Maybe.
If you are novice you shouldn't add all those above. Just start your site with a captcha and see how it goes. And deal with possible spam as you go.
About how to change the email templates you better ask at Wordpress.org, personally i have no idea.
Personally i use The Shield plugin for all my security needs, spam included.