Simple, when you visit a product page that allows subscriptions you will be given the option of 'One time purchase' or 'Save X% with U-Subscribe'.
Click on the U-Subscribe button and select your delivery interval. Pay for your first order and that's it, you're subscribed.
When you place your first order you will pay using your chosen payment method. We will then use this payment at every payment interval to take payment for your next delivery.
We will dispatch your items at your chosen interval from the date of your first order. So, if you have chosen a weekly delivery we will dispatch your items one week from your first order and then every week on the same day from that point unless you choose to cancel or change your subscription.