At the artistsinfo.co.uk website, click on the 'Login' link in the navigation.
At the next screen, enter the email address that you used when registering, and the password that you chose / were given. Click 'Log In'.
You may need to complete what's called a Captcha screen to continue. This is a way of protecting the site against malicious login attempts. If you see such a screen, just enter the character string that you see to continue.
If you cannot login, or have forgotten your password, click on the 'Lost Your Password' link un der the login button and follow the instructions to recover your password.