Sorry about the slight misunderstanding earlier.
One thing I noticed in your HTML code, is that you wrapped the username and password inputs into separate forms. What this means, is that if you were to submit the form, it would only return either the username or the password - not both. If there is any data you want to submit that is relative to each other (such as a username and password for a login system), you can place it all in one form to allow you to receive all of the necessary information for your back-end server script to function with.
If you wanted to submit the data separately, the layout you have now would work, but you'll only cause the handling of the data to be a lot slower as opposed to having it all handled in one fell swoop.
Another suggestion would be that you have an <input> tag that has its type set to "submit", as this will be what triggers the submission of your form without the intervention of JavaScript to send the form for you. The submit type <input> tag will be your Submit button as shown in the illustration.
In regards to you wanting to know how to change the colours of the boxes, you'd want to look into the
background CSS properties.
Just a helpful hint - you can assign a CSS class to individual <input> tags just as you can assign them IDs.