Layout for LJs

[vanilla_ofuda]

Okay, I've just made a new LJ account for an RP group on LJ, and I want to know how to simply add a border on top of the LJ page, without changing anything much. I know SOME of my friends do it, but I can't for the life of me remember who... and I'm not going to attempt to try anything as hard as this one before. 8D;
sylc, was it you? HELP? T___T