Nifty Web 20 only helps with content posting and not account creation so you will have to buy accounts from somewhere else or make them manually. I usually buy web 20 accounts from fiverr like this one:
You can buy 50 web 20 accounts for only $10.
To add these accounts in Nifty Web20 follow these steps :
1. Click on Save button in account section on top. It will open a window to add accounts.
2. Enter your website (complete URL with http tag), username (username or email address) and password
3. Make sure each line in all three boxes have data for same site and also each box should have same number of lines
4. Now click on add button and enter a filename in any location. This account data will be saved in that location.
5. Now click on load in account section and select this file and all your accounts will be loaded.
Every time you create a new instance of Nifty Web20 you can load this file and all the accounts will be loaded. You can then right click on any site, click open and press F1 and F2 to enter your username and password and then login.