The showcase function of AliExpress means that sellers can display some of their key products or activities on the homepage of the store to attract the attention of customers. Using the showcase function can increase the exposure and conversion rate of the store. The following are the specific steps to use the showcase:

1. Log in to the AliExpress Seller Center and enter the "Store Operation"-"Window Decoration" page.

2. In the "Window Decoration" page, you can choose to add modules such as window advertisements, event banners, popular products, etc., and choose according to your needs.

3. After adding, you can edit each module, including uploading pictures, setting titles, descriptions, links and other information.

4. After clicking "Save", re-enter the store homepage to see the showcase display effect.

It should be noted that the use of the showcase function requires certain design capabilities and marketing strategies, and requires accurate positioning and creative design based on target customers and product characteristics to achieve the best results.