Customize SharePoint Default List Forms Part 1

Creating a SharePoint list is hella easy. Point and click - and bingo - you have a form to type in and maintain your data in a structure you specified, and you can then create various views on the data collected.

But what if you wished to customize either the "New" form, or the "Update" form etc?

we can find the answer from this blog Customization of Newform.aspx