Chinese grammar: Purpose with 为了weile

为了 (wèile) is most often used to indicate the purpose of an action, or the person that will benefit from some act of kindness. In the "purpose" sense, it corresponds pretty well to "in order to" or "for the purpose of" in English.

为了 as a preposition

When 为了 indicates the purpose of an action, it's usually acting as a preposition. In this role, the whole "为了 phrase" should come before the verb.

Note also that 为了 is a single word; the 了 here is not serving its role as a particle in this case.

Structure 
为了+[some purpose],subject+predicate

Examples 

Wèi le qián, tā chū mài le pénɡ you.
为了 钱 ， 他 出卖 了 朋友 。

(money is the purpose) He betrayed his friends for money.

为了 as a verb

Occasionally you will see 为了 acting as a verb by itself. In this case, it usually combines with 是, and the meaning is not hard to derive: "to be for."

Structure 
subject+（是+）为了+objective

Example 

Wǒ zhè me zuò shì wèi le nǐ.
我这么做 是 为了 你 。

Did is for you.