My subscription is on hold. I want to make a payment to reactivate it. How do i do it?

Because you are already subscribed and your subscription is just on hold, you cannot add the course to your cart because that would create a new subscription. You will need to sign in, click "Account">>> "My Subscription">>> scroll down to where it says "Related Orders" and click "Pay". This will take you to a screen to enter your information and pay for that subscription.