"grasp how to" is correct and usable in written English.
You can use it when you are talking about learning how to do something. For example, "I am trying to grasp how to play the guitar."
He never seemed to grasp how to go about it.
But before I could grasp how to grow vines in the pumpkin patch, I needed to get a handle on squash taxonomy.
The F.D.A. had concluded, based on the best scientific evidence, that the pills are safe and effective and that adolescent girls can easily grasp how to use them.
Israelis worry that he will talk to Iran rather than stop it from developing nuclear weapons; Georgians worry that he will not grasp how to handle Russia.
He has been open enough to admit that joining Westminster was a shock to the system, initially finding it disorientating and unable to grasp how to measure success as a backbench MP. "It was so different from doing everything else".
You must understand the workings of the stock market before you can grasp how to succeed.
One lesson they clearly grasped: how to win at home.
Only Mitchell Starc in any way grasped how to play at Galle.
Designers grasped how to do edgy that wasn't ugly, desirable that wasn't flash.
The argument that if we grasped how to control the climate then evildoers would already be doing it doesn't hold water with conspiratorial thought, however.
If, as well as that scattered brilliance, there are some sections that are too diffuse, and a sense that Wallace hadn't yet grasped how to make the whole thing hang together, it's hard to feel disappointed.
