To create your own npm package for downloading TikTok videos, you will need to perform the following steps:

1. Install Node.js and npm on your computer.

2. Create a new directory for your package and navigate to it in the command line.

3. Run the command npm init to create a package.json file for your package.

4. Install the necessary dependencies for your package. For example, you may want to use a package like "tiktok-scraper" to scrape the TikTok website and extract video URLs.

5. Write the code for your package in a JavaScript file, such as index.js. This file should include functions for downloading TikTok videos using the dependencies you installed in step 4.

6. Test your package by running it from the command line and ensuring that it functions as expected.

7. Publish your package to npm by running the command npm publish.

Keep in mind that TikTok has specific terms of service that prohibit the unauthorized download of videos from the platform. You should make sure to read and understand these terms before publishing your package.