Points are spent on samples, if you run out of points there are a few ways that you can buy more.
Click on the account icon and then press buy more points
Or select buy more point from the cog menu
Or if you are trying to buy a sample or pack and do not have enough points
In each case, a webpage will open allowing you to purchase 500, 2000, or 5000 points.
As soon as you have completed the transaction your points will be added to your account.