2
the most straight-forward way of accomplishing this is with the following SQL query:
UPDATE <prefix>_users SET posts = posts + 10 WHERE uname = '<username>'
Where <prefix> is the database table prefix you chose during installation and <username> is the user's name.
You will need a tool that lets you run direct SQL queries in order to run this. If you do not already have a tool for this purpose, I'd recommend the
PHPMyAdmin module