The method is as follows:

1. Open WeChat, click the+icon in the upper right corner and select "Join Group Chat".

2. Enter "Zhengzhou City" in the search field, and then click the search button.

3. Find the right Zhengzhou city group in the search results, and then click the group link.

4. On the open page, click the "Join Group Chat" button and wait for the administrator to approve it before joining the group chat.