Add a Spinner on a Visualforce Page

Add the following snippet to your visualforce page:

<apex:actionStatus id="pageStatus">
    <apex:facet name="start">
        <apex:outputPanel >
            <img src="/img/loading32.gif" width="25" height="25" />
            <apex:outputLabel value="Loading..."/>
        </apex:outputPanel>            
    </apex:facet>
</apex:actionStatus>

Command Button :

<apex:commandButton action="{!doSomeAction}" rerender="rerenderId" status="pageStatus" value="Do Action"/>

The final rendered spinner will look like this:

 Loading…