How to use <apex:toolbarGroup>  in Visualforce Page?

<apex:toolbarGroup> :
A group of components within a toolbar that can be aligned to the left or right of the toolbar. The < apex:toolbarGroup > component must be a child component of an < apex:toolbar >.

This tag supports following attributes:

Attribute	Description
id	An identifier that allows the toolbarGroup component to be referenced by other components in the page.
itemSeparator	The symbol used to separate toolbar components in the toolbarGroup. Possible values include "none", "line", "square", "disc", and "grid". If not specified, this value defaults to "none".
location	The position of the toolbarGroup in the toolbar. Possible values include "left" or "right". If not specified, this value defaults to "left".
onclick	The JavaScript invoked if the onclick event occurs that is, if the userclicks the toolbarGroup.
ondblclick	The JavaScript invoked if the ondblclick event occurs that is, if the user clicks the toolbarGroup 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 toolbarGroup component.
onmouseover	The JavaScript invoked if the onmouseover event occurs that is, if the user moves the mouse pointer over the toolbarGroup 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.
separatorClass	The style class used to display the toolbar component separator, used primarily to designate which CSS styles are applied when using an external CSS stylesheet. See also the itemSeparator attribute.
style	The CSS style used to display the toolbar group, used primarily for adding inline CSS styles.
styleClass	The style class used to display the toolbar group, used primarily to designate which CSS styles are applied when using an external CSS stylesheet.

Visualforce Example:

<apex:page id="thePage">

    <apex:toolbar id="theToolbar">

        <apex:outputText value="Sample Toolbar"/>

        <apex:toolbarGroup itemSeparator="line" id="toobarGroupLinks">

            <apex:outputLink value="http://www.salesforce.com">salesforce</apex:outputLink>

            <apex:outputLink value="http://developer.salesforce.com">apex developer network</apex:outputLink>

        </apex:toolbarGroup>

        <apex:toolbarGroup itemSeparator="line" location="right" id="toobarGroupForm">

            <apex:form id="theForm">

                <apex:inputText id="theInputText">Enter Text</apex:inputText>

                <apex:commandLink value="search" id="theCommandLink"/>

            </apex:form>

        </apex:toolbarGroup>

    </apex:toolbar>

</apex:page>

How to use <apex:pageMessage>  in Visualforce Page?

<apex:pageMessage> :

This component should be used for presenting custom messages in the page using the Salesforce pattern for errors, warnings and other types of messages for a given severity. See also the pageMessages component.

This tag supports following attributes:

Attribute	Description
detail	The detailed description of the information.
escape	A Boolean value that specifies whether sensitive HTML and XML characters should be escaped in the HTML output generated by this component. If you do not specify escape="false", the character escape sequence displays as written. Be aware that setting this value to "false" may be a security risk because it allows arbitrary content, including JavaScript, that could be used in a malicious manner.
id	An identifier that allows the component to be referenced by other components in the page.
rendered	A Boolean value that specifies whether the component is rendered on the page. If not specified, this value defaults to true.
severity	The severity of the message. Values supported are: 'confirm', 'info', 'warning', 'error'
strength	The strength of the message. This controls the visibility and size of the icon displayed next to the message. Use 0 for no image, or 1-3 (highest strength, largest icon).
summary	The summary message.
title	The title text for the message.

Visualforce Example:

<apex:page standardController="Opportunity" recordSetVar="opportunities" tabStyle="Opportunity" sidebar="false">

    <p>Enter an alphabetic character for the "Close Date," then click Save to see what happens.</p>

    <apex:form >

        <apex:pageBlock >

        <apex:pageMessage summary="This pageMessage will always display. Validation error 

           messages appear in the pageMessages component." severity="warning" strength="3" />

        <apex:pageMessages />

        <apex:pageBlockButtons >

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

        </apex:pageBlockButtons>

            <apex:pageBlockTable value="{!opportunities}" var="opp">

                <apex:column value="{!opp.name}"/>

                <apex:column headerValue="Close Date">

                    <apex:inputField value="{!opp.closeDate}"/>

                </apex:column>

            </apex:pageBlockTable>

        </apex:pageBlock>

    </apex:form>

</apex:page>