making a div appear on bottom of another div

making a div appear on bottom of another div

i have this div used as an information container on my page, i want to
make a read more button on the bottom of the first div but cant do it, i
tried position:relative and every other method i know to accomplish this
but couldn't make it. any suggestion
<div class="main_banner" style="margin-left:46px;">
<center><b><h3
style="color:purple;padding-top:2px;margin-bottom:0">header1</h3></b></center>
<centeR><img src="images/pic1.png" width="275px"
height="103px" /></center>
<p class="index_services_p">some text</p>
<br>
<a style="padding-top:2px;float:left;padding-left:10px;" href="#"
style="float:left"><img src="images/read-more.png" width="172px"
height="32px" /></a>
any suggestions will be appritiated.