To book accommodation at Yangxin Valley Castle in Yichun, you can follow the following steps:

1. Open WeChat and click "Service" in "My".

2. On the service page, click "Hotel".

3. On the hotel page, enter Yichun Yangxin Valley Castle and search.

4. Click this option after you find the castle of Yangxin Valley in Yichun.

5. Finally, select the accommodation type, and click the Booking button to complete the booking.

Please note that the specific booking process may be different for different platforms and hotels. It is recommended to read the relevant terms and policies carefully before booking, and make sure to provide correct information and payment methods.