To do this, click your name at the top of your MyCase account and click 'Upgrade Today' (see below).
Once this is clicked, you can enter in your billing information.
When you click to save your billing information, your credit card will be charged that day. Charges will be based on the number of firm users and any other services. MyCase has a flat $69 per month, per user rate. Applicable sales tax may apply.
After you enter your billing information, you can also choose whether your subscription should be billed monthly or annually (see image below) by going to your Settings > Firm Settings.