Smooth Ajaxified Contact form that sends the data to email with spam control, database save option, form styling option and admin settings.
Where can I find the settings to adjust the plugin work after activation? In the WordPress Dashboard sidebar Menu, you can find a link "MN Contact Form" to the settings page.
After the plugin installation I haven't adjusted the settings. What is the default email address used for a contact via the form? The address specified during WordPress installation will be used by the Contact Form plugin as the default one. Basically it is your super user email address set under Settings ->General ->General Settings
How can I add Contact Form to my website? You should put the shortcode [mn_contact_free] into your page or post. Alternatively you can also use the wordpress widget named "MN Contact form" into any sidebar location.
How can I set a default reply mail for the user? Once you activate the plugin, in the admin menu "MN Contact Form" -> MN Contact Form Settings, you can find an option to set the reply mail address and reply message for the emails to be sent to the user who has submitted the contact form.