Magento includes contact form functionality by default. 
A link to a contact form can usually be found in the footer of your Magento installation.

Of course, you can add a contact form on any page. All you need to do is:

• Log in to the administrator area.

• Go to CMS > Pages.

• Select the page you want to edit or create a new page.

Paste the following code using the HTML option of the WYSIWYG editor:

<!– CONTACT FORM CODE BEGIN–>

{{block type='core/template' name='contactForm' template='contacts/form.phtml'}}

<!– CONTACT FORM CODE END–>

Save the changes and the contact form will appear on the desired page.