#sidemenu{
font-fanily: "Arial", Verdana, Helvetica, sans-serif;
font-size: 100%;
width: 220px;
margin-right: 8px;
float: right;
text-align: left;
}

mispelt font-family, thats something easy to fix.

a: visited{
color: #000000;
text-decoration: none;
}

a: hover{
color: #000000;
}

no space should be between the a: and the next work, make them a:visited and a:hover.

Thats all I see that should make it valid.

Too make it better, well, I'm new to this so talk to someone who knows a lot about it.