A is not B, but/and...
When we want to put these negative forms into て-form, *all we need to do is drop the last い of ない and add くて.
～くない → ～くなくて
～じゃない → ～じゃなくて
(↑ An exception to this rule is ～では［じゃ］ありません, as it doesn't end in ～ない. In this case, we could just change it to ～ではなくて or ～じゃなくて.)
てんき が よくなくて ざんねん でした。
Unfortunately, the weather was bad. // The weather was bad, which was disappointing.
Literally: "weather + が + not good (and) + disappointing + でした (=was)."
I'm not sure if we mentioned this before, but if you want to write いい (good) using kanji, it's 良い. However, the reading with kanji is typically よい, not いい.
Let's say that your friend Nagisa is picking you up at your house so that you can go to lunch together. You're walking out to the street, and you see a car parked right in front of your house, so you ask:
これ が なぎさ の くるま？
This is your car?
Literally: "this + が + Nagisa + の + car?"
Nagisa corrects you, saying:
ううん、 これ じゃなくて あれ。
No, not this one, that one.
Literally: "no, + this + isn't (and) + that (over there)."
I hope so because this lesson is over! *_*