Use a "how" clause when you want to say something about a fact. For example, here's a fact:
Most American people don't even own a bike.
And here's a sentence that's talking about this fact:
We were talking about how most American people don't even own a bike.
Here are a few more examples:
I love how he just stands there and watches while I do all the work!
(This is said sarcastically.)
It's crazy how you can live so close to somewhere like this and never even know that it existed.
"How" clauses like this usually come after the verb. It's not common to use a "how" clause this way at the beginning of a sentence.