How to use apex:pageBlockButtons In Visualforce page?

apex:pageBlockButtons:

                   Whenever <apex:commandbutton> tag is used, a button is created in a based on the position where the tag is written.  But most of the times, we may want to place the buttons on the top or bottom of the page. This can be achieved with the help of this tag. 

              This component must be a child component of an < apex:pageBlock >.

This tag supports following attributes:

Attribute	Description
dir	The direction in which the generated HTML component should be read. Possible values include "RTL" (right to left) or "LTR" (left to right).
id	An identifier that allows the pageBlockButtons component to be referenced by other components in the page.
lang	The base language for the generated HTML output, for example, "en" or "en-US".
location	The area of the page block where the buttons should be rendered. Possible values include "top", "bottom", or "both". If not specified, this value defaults to "both". Note that if a pageBlock header facet is defined, the facet overrides the buttons that would normally appear at the top of the page block. Likewise if a pageBlock footer facet is defined, the facet overrides the buttons that would normally appear at the bottom of the page block.
onclick	The JavaScript invoked if the onclick event occurs--that is, if the user clicks anywhere in the pageBlockButtons component
ondblclick	The JavaScript invoked if the ondblclick event occurs--that is, if the user clicks the pageBlockButtons component twice.
onkeydown	The JavaScript invoked if the onkeydown event occurs--that is, if the user presses a keyboard key.
onkeypress	The JavaScript invoked if the onkeypress event occurs--that is, if the user presses or holds down a keyboard key.
onkeyup	The JavaScript invoked if the onkeyup event occurs--that is, if the user releases a keyboard key.
onmousedown	The JavaScript invoked if the onmousedown event occurs--that is, if the user clicks a mouse button.
onmousemove	The JavaScript invoked if the onmousemove event occurs--that is, if the user moves the mouse pointer.
onmouseout	The JavaScript invoked if the onmouseout event occurs--that is, if the user moves the mouse pointer away from the pageBlockButtons component.
onmouseover	The JavaScript invoked if the onmouseover event occurs--that is, if the user moves the mouse pointer over the pageBlockButtons component.
onmouseup	The JavaScript invoked if the onmouseup event occurs--that is, if the user releases the mouse button.
rendered	A Boolean value that specifies whether the component is rendered on the page. If not specified, this value defaults to true.
style	The style used to display the pageBlockButtons component, used primarily for adding inline CSS styles.
styleClass	The style class used to display the pageBlockButtons component, used primarily to designate which CSS styles are applied when using an external CSS stylesheet.
title	The text to display as a tooltip when the user's mouse pointer hovers over this component.

Example:

<apex:page standardController="Account">

    <apex:form>

        <apex:pageBlock title="My Content" mode="edit">

            <apex:pageBlockSection title="My Content Section" columns="2">

                <apex:inputField value="{!account.name}"/>

                <apex:inputField value="{!account.site}"/>

                <apex:inputField value="{!account.type}"/>

                <apex:inputField value="{!account.accountNumber}"/>

            </apex:pageBlockSection>

            <apex:pageBlockButtons>

                <apex:commandButton action="{!save}" value="Save"/>

            </apex:pageBlockButtons>

        </apex:pageBlock>

    </apex:form>

</apex:page>

The above code generated the below page: