This easel card is so easy to do! All you have to remember is to fold things in HALF - no need to remember complicated measurements.
I've used the big wave stamp from the Waves of Inspiration stamp set as well as images from the Let's Set Sail bundle.
Simply fold your card base in half and then fold the front of the card back in half again to meet the fold in the middle. This creates the easel shape.
Then create a "stopper" to hold your card in the easel shape. I've used a punched sentiment raised on Dimensionals to achieve this.