Click on the earn tab as below:
On the top of Earn & Invest in the tob bar, swipe left to find the block with CANNACOIN 2-5% written and tap on the arrow, as in the image below:
Now tap Lock funds, as in the image below:
Enter the amount of CANNACOIN you would like to stake, and choose the length of your lock up period.
The longer the lock up period the higher the annual percentage yeild (APY) will be.
Now click on Proceed, as in the image below:
Refer to the video demonstration below: