To buy things in Pinduoduo live room, you can follow the following steps:

1. Open the Pinduoduo app and log in to your account.

2. Enter the keyword or category of the product you want to buy in the app homepage or search bar, and click Search.

3. In the search results page, filter out the "Live" option and select the live broadcast room you are interested in.

4. After entering the live broadcast room, you can choose the products you want to buy by watching the products and promotion information recommended by the live broadcaster.

5. Click on the product picture or title to enter the product details page, you can view the product introduction, specification, price and promotion information on this page.

6. If you decide to buy the item, you can choose the quantity, color and other options of the item (if any), and then click the "Buy Now" button.

7. On the confirmation order page, fill in the delivery address and other relevant information, and select the payment method.

8. Finally, click "Submit Order" and complete the payment.

Please note that the products and promotions in Pinduoduo's live broadcast room usually have time limits and inventory restrictions, so you need to place an order to pay as soon as possible when snapping to ensure a successful purchase. At the same time, you also need to pay attention to the after-sales service policies of commodities, including returns and exchanges, quality assurance, etc.