1. Explain it simply
着 after a verb shows an ongoing state or the manner of an action.
门开着 means the door is (staying) open; 他站着看书 means he reads while standing.
着 attaches right after its verb and stays there.
Don't move 着 to the front or the end of the sentence.
2. Show examples
门开着。
Mén kāizhe.
The door is open.
ongoing state
他站着看书。
Tā zhànzhe kàn shū.
He reads standing.
manner: V着 + V
灯开着。
Dēng kāizhe.
The light is on.
着 right after the verb
3. Share a tip
着 sits directly after its verb to mark an ongoing state; moving it to the front or end makes the sentence wrong.

