Data Entry: adding new users to a site

Dear all, we need to add 7500 new users to an our existing website. We need to reach 10.000 users and actually we have 2500 users to our site. We need that you start subscribing, one by one, 7500 new users in a website: each user must have a personal email(you can create by yourself emailor add users that you know). Our target is having 7500 fresh new users fastly (20 days from now).