I'd recommend that you use jquery.
First, I'd set up each form how you like it, and put each in its own DIV. Give each div a unique ID.
Then in the CSS, set each form div to 'display: none'
Then set up the buttons so that when clicked, they show the form. With jquery, this is pretty simple:
You may want to set it so that the other forms are hidden when the user clicks a button. For example, if the user clicks button #2 while form #1 is visible, it hides form #1 and shows form #2. In that case you can just give each form DIV the same class and use jquery hide() all those, then show the required one.
Hope that helps.