Sometimes automatic emails from an unfamiliar website can be marked as spam or junk email by some email programs or email providers. The first thing to do is to check your spam or junk folder. If you find the welcome email there, you can mark it as "not spam" or the equivalent, and you should be able to proceed as normal by clicking on the link in the email.
If you don't find the email in your junk/spam folder, it's possible that you have entered your email address incorrectly when registering. The way to check this is to try to register on the site again, with the same email address. If you are successful then the problem was probably a typo in the email address.
Finally, it is possible that the email has simply been delayed. Emails are sent immediately from our system but occasionally can be held up "downstream" by the email receiving system. If you still don't receive your welcome and verification email after a couple of hours, contact support and we will activate your account for you.