Hi Yogesh,
I am refering an example for popup window:-
<apex:pageBlock >
<apex:commandButton value=”show popup” action=”{!showPopup}” rerender=”popup” status=”status”/><apex:outputPanel id=”popup”>
<apex:outputPanel id=”popInnerOutputPnl” styleClass=”customPopup” layout=”block” rendered=”{!displayPopUp}”>
<apex:commandButton value=”X” title=”Close the popup” action=”{!closePopup}” styleClass=”closeButton” rerender=”popup”>
</apex:commandButton>
<apex:pageblockSection >
<apex:pageblockSectionItem >
<apex:outputLabel value=”Email” for=”address”></apex:outputLabel>
<apex:inputField id=”address” value=”{!Contact.Email}”/>
</apex:pageblockSectionItem>
</apex:pageblockSection>
<apex:commandButton value=”Ok” action=”{!redirectPopup}” styleClass=”closeButton” rerender=”popup”>
</apex:commandButton>
</apex:outputPanel>
</apex:outputPanel>
</apex:pageBlock>