To set up a promotion plan on Taobao, you need to follow the steps below:

1. Log in to your Taobao seller account and enter the Seller Center.

2. On the Seller Center page, find and click the "My Promotion" option.

3. On the "My Promotion" page, you can see the relevant options for the promotion plan. Click "Set Up Promotion Plan".

4. On the Settings page, you can choose the type of promotion plan you want to set up. For example, you can choose search promotion, diamond exhibition promotion, through train promotion, etc.

5. Fill in the relevant information according to the type of promotion plan you choose. For example, if you choose search promotion, you need to set keywords, bids, etc.

6. After filling in the relevant information, click the Confirm or Save button to submit.

Please note that you have a detailed understanding of the specific requirements and cost information of the promotion plan, and conduct sufficient market research and plan formulation before formulating the promotion plan to ensure that the expected promotion effect can be achieved.

In addition, since the interface of the Taobao platform may change according to time and region, the above steps may be slightly different. If you have specific questions, it is recommended that you consult the official Taobao Help Center or contact Taobao customer service for more detailed guidance.