My sidebar only has “categories”. How do I add other stuff?

Here’s my blog. I deleted all my posts, because when I was trying to figure this out I read a forum thread that sounded like maybe if one of your posts or images is too big, it crowds out the sidebar. Or something like that.

Anyway, that clearly doesn’t apply in my case.

I just want to know how to add common sidebar elements like “contact” and “blogroll” and “links”. And also how to customize the sidebar stuff, because I’ll want a link to my web home page, and to other pages on my website when I build them.

Thanks for help, anyone!