Step 1: First click on the user's avatar and enter his homepage. Then you will see a "Product Showcase" under his homepage name and click on "Product Showcase".

Step 2: After clicking into the showcase, you can see that there are two options, the first is "My" and the second is "Recommendation". If you don't see what you want in "My", you can click Recommendation to enter another page

Step 3: Click on what you want to enter the purchase interface.

Step 4: After clicking to enter the purchase page, click "Buy Now" to buy what you want

Finally, I want to tell everyone that if you buy things, you must choose a large platform like Douyin.