Summarize this article:

You will need to find a site that is vulnerable, due to an easily accessible admin login. Try searching on your favorite search engine for admin login.asp or admin login.php. Type admin as the username and use one of a number of different strings as the password. These can be any one of a number of different strings but a common example is 1'or'1'='1 or 2'='2. This is probably going to require a little trial and error. Eventually, you should be able to find a string that allows you admin access to a website, assuming the website is vulnerable to attack. Then, logged in as an administrator, you can perform further actions, such as uploading a web shell to gain server-side access if you can perform a file upload.

Summary:
Find a vulnerable site. Login as an admin. Be patient. Access the website.