if you did not pass the payment section yet, see @RossN 's post.
If you want to try this during working hours for activating..click this link to use the: Public Mobile Online Activation Assistance
BUT-If you got past the payment section of the activation pages, try the SIM into the phone and reboot the phone. Do you have any services? If so, and if you can log into My Account then you activated that SIM card.