how to show alert in html page

[kakas]

how to show alert in html file while using four pages in single index.htmlusing paging.I want that when page_two is clicked it show alert when that page is load\[code\]<div class="menu"><ul> <li><a href="http://stackoverflow.com/questions/12795488/#index"><img src="http://stackoverflow.com/questions/12795488/images/mockup4_22.png" /></a></li> <li><a href="http://stackoverflow.com/questions/12795488/#page_one"><img src="http://stackoverflow.com/questions/12795488/images/mockup4_24.png"/></a></li> <li><a href="http://stackoverflow.com/questions/12795488/#page_two"><img src="http://stackoverflow.com/questions/12795488/images/mockup4_26.png" id="check"/></a></li> <li><a href="http://stackoverflow.com/questions/12795488/#page_three" ><img src="http://stackoverflow.com/questions/12795488/images/mockup4_28.png" id="btn" /></a></li> <li><a href="http://stackoverflow.com/questions/12795488/#page_four"><img src="http://stackoverflow.com/questions/12795488/images/mockup4_30.png"/></a></li></ul>\[/code\]