To add a custom page to the navigation bar at the top of the mobile Taobao homepage, follow the steps below:

1. Log in to the Taobao APP and click [My Taobao] at the bottom.

2. On the [My Taobao] page, click the gear icon in the upper right corner to enter the [Settings] menu.

3. In the [Settings] menu, scroll down and find [Shop Management] and click to enter.

4. On the [Shop Management] page, find [Self-operated Module] and click to enter.

5. On the [Self-operated Module] page, find [Taobao Coin Channel] under the [Taobao Coin] column and click to enter.

6. On the [Taobao Coin Channel] page, click the [Create Now] button below to enter the Create Event page.

7. On the Create Event page, select [Custom Page] and follow the prompts to edit the page content, title and other information.

8. After editing, click the [Publish] button in the lower right corner to add the custom page to the navigation bar at the top of the Taobao mobile homepage.

It should be noted that only merchants who meet certain conditions can create custom pages. For specific conditions, please refer to the relevant regulations of Taobao.