There are quite a few words in Russian that express the idea of needing something or needing to do something. One of the most common is a short form adjective: нужен, нужна, нужно, нужны. From the English point of view the construction associated with the word has a few quirks. First off, the word is a predicate adjective, which means it has to agree with it's subject. So if a book is needed, you say «Книга нужна». If milk is needed you say «Молоко нужно». The person who needs the item shows up in the dative case. Thus «Машина нужна Борису» “A car is necessary to Boris.” Despite the fact that the car is grammatically the subject of the sentence, in conversation it usually ends up at the end of the sentence, and the person usually ends up at the beginning. Thus the last example sentence usually comes out «Борису нужна машина». Here are some sample sentences:

To put the sentences in the past or future, you add forms of the verb “to be.” Since the thing you need is the subject, it determines the ending on the verb.