That is easy to Fix.
The reason it doesn't work, Is cause your Java isn't Installed Properly, That is normal on Windows 7, But can Easily be Fixed.
And Since the Java isn't installed Properly, When you try "Run" your Client; It wont be able to find the right Path.
Which means that what you gotta do, Is install it properly, So that it follows the Right Path. This can be looked up on YouTube,
By searching, "How to install Java on Windows 7."
If no Videos are able to Help you, Please tell me, And i will help.
Thanks, Tony.