When used as a resultative complement, 着 (zháo) expresses that the action has reached it's purpose or has had an outcome. It can also be used as a potential complement, meaning "able to."
All you have to do is put 着 after the verb. Remember that it should be something that you can reach or achieve. It could be a purpose, or it can be producing an outcome or an influence.
Verb + 着
Verb + 得 / 不 + 着
When used with 得 or 不, 着 functions as a potential complement, and denotes that one's one's ability is up (or not) to the task in question. This is like saying "(verb) able to reach" or “(verb) not able to reach."