The particle に plus a motion verb can be used to express purpose :

レストランにカレーを食べに行きました = I went to the restaurant to eat curry.(Or, I went to the restaurant for the purpose of eating curry. Or, I went to the restaurant in order to eat curry.)

(レストラン = restaurant. に = to. カレー = curry. を = particle. たべ/食べ = eat. に = to. いきました/行きました = went)

To express a sentence for the purpose of doing something, use this formula :

Location/destination + に + purpose + に + motion verb.

Using the example above :

The location/destination  = レストラン (restaurant)

+ に (to)

Purpose = 食べ (eat curry)

+ に (to)

Motion verb = 行きました (went)

Here’s another example using this formula :

彼は花やに花を買いに来ました = He came to the flower shop to buy flowers. (Or, he came to the flower shop for the purpose of buying flowers. Or he came to the flower shop in order to buy flowers.)

(かれ/彼 = He. は = particle. はな/花 = shop. や = shop. に = to. はな/花 = flower. を = particle. かい/買い = buy. に = to. きました/来ました = came)

Now try making sentences of your own for practice. Here are some other motion verbs that you can use :

かえる/帰る (to return [to a place])

もてる (to return [something])

でかける/出かける (to go out)

でる/出る (to leave)