You need to customize the NewForm.aspx page of the list. You can customize the form either in SharePoint designer. Example:
http://blah.winsmarts.com/2007-5-Customize_the_-and-quot;NewFormaspx-and-quot;_page_for_a_SharePoint_List.aspx
https://sharepoint07.wordpress.com/2008/02/05/customize-the-newformaspx/
Or you can create a web part (Visual webpart will make life easier as it has a design surface) and then drop this web part on the NewForm.aspx page of the list and hide the web part which is already present and rendering the data as it is right now. Apart
from the required design, the web part will have code to insert the list items.
Note: If you go by first approach, then make sure to keep a backup of the existing NewForm.aspx page before you do customizations. In case something goes awry you can fall back to original copy.