The first thing you need to do is to login into your blogger dashboard. Now go to Your Blog >> Layout >> Add a gadget >> More >> Contact Form widget. Check out the following screenshot for a detailed guide. Once done, move to the next step.
Now rename the title of the widget and once everything is done press “Save” button located at the bottom of the window.
Congratulations: The built-in Contact us Widget is added to your site. Visit your site and confirm that the widget is successfully integrated in your sidebar.
The features of this widget are somewhat like an ordinary contact us form, or in other words you can say that it is pretty much like simplicity at its best. It has three files one for the email address, the second for the name and the third is finally for the message.
The good thing is that this widget supports Email validation. Which means, when someone would enter an invalid email address it would display an error message such what similar to the following screenshot (A valid email address is required).
This widget does not support Captcha codes, which means that you would receive spammy emails if someone attacked your gadget through a robot or any other software. There are still few bugs in the gadget, but comprehensively it is indeed a much needed improvement. Now most of the folks can easily add a contact us form without even hosting it on a host. However, if you mean real business, then this contact us page might not help you greatly.