You draw the footboard towards yourself to get into the catch position.

The concept of drawing the boat underneath you to get into the catch position is not commonly coached and even less when it comes to erging on stationary rowing machines. 

Here is what you need to look for when you row, no matter what you sit on: Complete your forward body angle before the rise of the knees and feel how your feet are pushing down against the heel restraints on the erg, and down towards the bottom of the boat when you row on the water.   A fitting analogy comes from cycling coaches who tell their riders to use the pedals at the bottom of their stroke as if they were trying to scrape mud of the bottom of their shoes.  When you row, seek to scrape the dirt of the bottom of your shoes and this will lead your knees to rise up.  There are many other ways to explain this.  If you have questions, never hesitate.  You can always call or text and this includes your parents. 

Have a great evening, 
Xeno