To show the state of becoming... something, use ~に なります ni narimasu.
The ni is placed after what something is becoming (or became, or might become... depending on the conjugation used, as the examples illustrate below).
The narimasu means to become. Nouns and -na adjectives use ni narimasu. -i adjectives are different, but for now there are enough useful nouns to look at:
* ~mashita shows past
* the ~mashou means "let's"