How To Add Html Codes To Blogger Posts

Copy the below code 

post blockquote {
background: #C8EFFF url
(http://2.bp.blogspot.com/-jSiMPSsf6Rs/
T4lHasB89hI/AAAAAAAABM4/nKdZmTXYrto/
s1600/1.png);
background-position:top left;
background-repeat:repeat-y;
margin: 0 20px;
padding: 10px 20px 10px 45px;
border-top: 2px solid #DDD;
border-right: 5px solid #666;
border-left: 2px solid #DDD;
border-bottom: 5px solid #666;
font-size: 0.9em;
}
.post blockquote p {
margin: 0;
padding: 0 0 15px;
}
.blockquote {
font: 18px normal sans-serif,Tahoma;
padding-top: 10px;
margin: 5px;
text-indent: 65px;
}
.blockquote div {
display: block;
padding-bottom:10px;
}
.blockquote p {
margin: 0;
padding-top:10px;
}