Change Case Owner VF Page

<apex:page tabStyle="Case" standardController="Case" extensions="ChangeOwner">
<apex:form >
<apex:sectionHeader title="Change Case Owner"/>
<p>This screen allows you to transfer cases from one user or queue to another. When you transfer ownership, the new owner will own:</p>
<ul><li>all open activities (tasks and events) for this case that are assigned to the current owner</li></ul>
<p>Note that completed activities will not be transferred. Open activities will not be transferred when assigning this case to a queue.</p>
<apex:pageBlock mode="Edit">
<apex:pageBlockButtons location="bottom">
<apex:commandButton value="Save" action="{!save}"/>
<apex:commandButton value="Cancel"/>
</apex:pageBlockButtons>
<br/><apex:pageBlockSection title="Select New Owner" collapsible="false" columns="3">
<apex:pageBlockSectionItem >
<apex:outputLabel value="Owner"></apex:outputLabel>
<apex:inputField value="{!Case.ownerId}"/>
</apex:pageBlockSectionItem>
</apex:pageBlockSection>
</apex:pageBlock>
</apex:form>
</apex:page>


public class ChangeOwner {
   
    public ChangeOwner(ApexPages.StandardController controller) {

    }

}