We don't offer an option to upload a list of sites to alexa.com at this time, however if you'd like to get rank, country, or backlink data for sites you can write a program to read the list and make requests to our Alexa Web Information Service API to get data for each site on your list.
To use the AWIS service you will need to follow these Getting Started steps: https://aws.amazon.com/awis/getting-started/.
After you get started, we recommend reading the Technical documentation here: http://docs.amazonwebservices.com/AlexaWebInfoService/latest/
And then modifying one of the sample programs here to get the data you are interested in: https://aws.amazon.com/awis/getting-started/#awis_sample_code.
The service uses tiered pricing. Pricing information is available on the main API page at http://aws.amazon.com/awis/.
Note that API access is not included with an alexa.com subscription plan.