Here are our docs on...
- Custom components: https://docs.retool.com/docs/custom-components
- Custom libraries: https://docs.retool.com/docs/custom-js-code#custom-javascript-libraries--npm-modules
- Custom libraries (community post): http://community.retool.com/t/how-do-i-use-external-libraries/3742/7
Let me know if you run into any issues 