To create Mysql Databases in Plesk 10.x, please follow the following steps :-
1) Login to Plesk control panel.
2) Click on "Subscriptions"
3) Click on Manage Hosting.
4) Click on "Websites & Domains".
5) Click on "Databases".
6) Click on "Add New Database".
7) Fill the reuqired fileds.
Database :
Type : You can select MySql and MSSQL as per your requirment.
8) Click OK and then Click on Add new Database User.
9) Fill the reuqired fileds.
Database User Name:
New Password :
Confirm Password :
10) Click Ok.