Become に　なります

To show the state of becoming... something, use ～に　なります ni narimasu The ni is placed after what is becoming something.  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:

夜　に　なりました。
yoru ni narimashita.
It has become night.
[~mashita shows past]

友達　に　なりましょう。
tomodachi ni narimashou.
Let's become friends.
[the ~mashou means "let's"]

げんき　に　なりました。
genki ni narimashita.
(I) have become fine / healthy.