The adverb "nicht" is used for everything but nouns (see previous lecture).
For example "nicht" is used to negate:

1 | adjectives: Du bist nicht nett. You are not nice
2 | verbs: Ich schlafe nicht. I don‘t sleep.
3 | articles (except the ein- ones): Du bist nicht mein Freund. You are not my friend.
4 | pronouns: Ich meine nicht dich. I don‘t mean you.

Where to put NICHT?

The overall rule is to put "nicht" in front of the information that you want to negate. The following sentence can be negated in different ways:

Ich habe dich gestern auf der Arbeit gesehen.

1 | Ich habe dich gestern auf der Arbeit nicht gesehen.
1 | I didn't see you at work yesterday.

2 | Ich habe dich gestern nicht auf der Arbeit gesehen.
2 | I didn't see you at work yesterday (but at the unemployment office).

3 | Ich habe dich nicht gestern auf der Arbeit gesehen.
3 | I didn't see you yesterday at work (but last Monday).

4 | Ich habe nicht dich gestern auf der Arbeit gesehen.
4 | I didn't see you at work yesterday (but your twin brother).

5 | Nicht ich habe dich gestern auf der Arbeit gesehen.
5 | Not I saw you yesterday at work (but my husband).

Examples 3, 4 and 5 are rather theoretical and almost never used in daily life. Hence we will ignore them.

Rules of Thumb

The English language is of quite little help here as you might see in the translations. But don't despair. The following rules cover 99% of all appearances of "nicht". Apply them in the given order. Be aware that in real life there might be derivations from these rules but in this course all exercises will follow this order:

1 | If there is a preposition involved, put the "nicht" in front of that preposition: Ich bin nicht auf der Arbeit.

2 | If there's no preposition and there's a past participle (the ge- word that you need to create the past or the passive) put "nicht" in front of it: Ich habe dich gestern nicht gesehen

3 | "nicht" goes in front of the information that you want to negate (see examples above).

4 | If you want to negate the action / the verb put nicht at the very end.

That will cover all of your needs until C1 but keep in mind that these are rules of thumb and not every situation might be crystal clear. That's fine.

Learning Advice

Whenever you get the chance to listen to native speakers, pick one day on which you will especially focus on how people negate things. This kind of focussing exercise will also pay off when you deal with other grammatical topics.