In one sentence, describe what the following article is about:

Just go to http://www.plagium.com/, and you will be brought directly to the main page of the website. Signing up is free. Just click on the "Sign in" button on the top right side of the screen, and enter your username and password. If you need to purchase searches before doing a long search, go to the "My Account" tab on the top right side of the screen. Once that page loads, scroll down to the "Payments" subheading, and click on "Refill My Search Credits" to add credits. The credit plans vary in prices depending on your particular search needs. Determine what suits your requirements. " Once you have your credits on file, go to the "Check Text" tab on the black banner towards the top of the page. You will see a text box below the black banner. This is where you enter the content that you want verified as original. You can either copy and paste the text in the box, or type it out. Below the text box you will see bubbles that read "The Web," "News," or "Social Networks." Select where you want Plagium to search for the text that you had entered. They will be displayed below the text box. You will be shown such information as source links, text that matched, and titles. The most important thing it shows is a box on the bottom corner of each place it found a match. It will say "Rank" and a percentage. This number reflects how much of the text found matches the text you entered. The lower the number the better!

Summary:
Go to the website and sign up. Sign in with your username and password. Buy credits. Set "Check Text. Enter the text. Tell Plagium where to look. Check the results.