Start by clicking on your profile on top right of the dashboard and selecting Billing on the drop-down menu.
In Billing, look for the Subscription section. Here you can see your current plan and its price. To view all the available plans and upgrade your current one, click Update plan below the current subscription.
In the Update plan view you can see all the plans and their features. You can switch between the monthly and yearly prices with by clicking the headings above. To select a plan, click Order now. If you do not yet have a payment card, you can add one in the window that pops up.