Website Functionality Fixes Needed

I'm seeking a skilled developer to address a couple of functionality issues on my website.

Key Tasks:
- Fix the issue preventing the site from sending out tracking numbers.
- Resolve problems with the new user sign-up process.

Ideal Skills and Experience:
- Strong background in web development.
- Experience with user authentication and backend functionality.
- Ability to troubleshoot and resolve issues efficiently.

Please provide examples of similar work done.