Sidebar problems with modifying classic

I’m trying to modify Classic so that it looks like the majority of WordPress themes out these days – fixed width, with the sidebar on the right. However, I can’t quite get it to work.I’ve got the sidebar so it’s no longer positioned in the right hand corner, and I’ve got it as part of the body of the theme, and it’s aligned right. However, it stays below the posts. See for yourself: http://winnopeg.com/images/wordpress_theme.png.

I can’t get it to lign up properly – how can I get it so it’s aligned top right (below the header though, please)?

The CSS file from the theme can be viewed/downloaded at http://winnopeg.com/dl/style.css.

Please help.