A: 瞧！谁坐在小马右边呢？
    Qiáo! Shuí zuò zài Xiăo Mă yòu bian ne?
    Look! Who's sitting on the right of Xiao Ma?

B: 是，老李。看见我的交通图了吗？
    shì, Lăo Lĭ. Kăn jiàn wŏ de jiāo tōng tú le ma?
    It's Lao Li. Have you seen my road map?

A: 看见了, 在桌子上边呢。
    Kàn jiàn le, zài zhuō zi shàng bian ne.
    Yes I've seen it, on the table. A: 你知道天安门在哪儿吗？
    Nĭ zhī dào Tiān ān mén zài năr ma?
    Do you know where Tian'Anmen is?

B: 在市中心。这就是天安门。
    Zài shì zhōng xīn. Zhè jiù shì Tiān ān mén.
    In the city center. This is just Tian'Anmen.

A: 故宫是不是在它北边？
    Gù Gōng shì bú shì zài tā bĕi bian?
    Is the Forbidden City located to its north?

B: 对，故宫在天安门北边。
    Duì, Gù Gōng zài Tiān ān mén bĕi bian.
    Yes, the Forbidden City is located to the north of Tian'AnMen.

Phrase structure

In a sentence with 在(zài) indicating existence, the subject is usually the person or thing concerned and the object is usually a noun denoting position or place.

Examples:

故宫在天安门北边。 The Forbidden City is to the north of Tian'Anmen.
书在桌子上边。 The book is on the table.
我在他右边。 I'm on his right.
他在我和她中间。 He is between me and her.

Some position words