in additional.css:
#ranks li {
    background: url(https://data.bugabuse.net/images/sprites/rank-sprite.png) no-repeat top left;
}
.sprite-admin{ background-position: 0 0; width: 157px; height: 44px; } 
.sprite-banned{ background-position: -207px 0; width: 157px; height: 44px; } 
.sprite-bugabuser{ background-position: -414px 0; width: 157px; height: 44px; } 
.sprite-coder{ background-position: -621px 0; width: 157px; height: 44px; } 
.sprite-donator{ background-position: -828px 0; width: 157px; height: 44px; } 
.sprite-exdonator{ background-position: -1035px 0; width: 157px; height: 44px; } 
.sprite-hondonator{ background-position: -1242px 0; width: 157px; height: 44px; } 
.sprite-legdonator{ background-position: -1449px 0; width: 157px; height: 44px; } 
.sprite-member{ background-position: -1656px 0; width: 157px; height: 44px; } 
.sprite-middleman{ background-position: -1863px 0; width: 157px; height: 44px; } 
.sprite-moderator{ background-position: 0 -94px; width: 157px; height: 44px; } 
.sprite-mudkip{ background-position: -207px -94px; width: 150px; height: 50px; } 
.sprite-newcomer{ background-position: -407px -94px; width: 157px; height: 44px; } 
.sprite-pikachu{ background-position: -614px -94px; width: 150px; height: 50px; } 
.sprite-recoverer{ background-position: -814px -94px; width: 157px; height: 44px; } 
.sprite-robot{ background-position: -1021px -94px; width: 150px; height: 50px; } 
.sprite-snorlax{ background-position: -1221px -94px; width: 150px; height: 50px; } 
.sprite-superdonator{ background-position: -1421px -94px; width: 157px; height: 44px; } 
.sprite-unicorn{ background-position: -1628px -94px; width: 300px; height: 100px; }


for the actual rank:
<ul id="ranks"><li class="sprite-newcomer"></li></ul>