I don't know what is wrong. Basic newbie trouble, I suppose.
ALL ADVICE IS GRATEFULLY WELCOMED!

I used the configure Atahualpa theme options to set width but it remains tiny and based on text in column. And I used the widgets menu to drag widgets to sidebars but I cannot configure them or even access categories or tag cloud.

I put in a post with a lot of tags but the tags don't show up in the sidebar tag cloud widget. I have a category menu across header but subcategories do not drop down. I cannot make category bar work at all or even show categories in side menu.

I actually want the same dropdown menu on the left sidebar but don't know how

I want to change configuration of archive and login widgets.

This is what site looks like now: http://anartist.biz/mccall/

it is in password-protected mode now--PW: bytesforall

Looks ok to me, did you change something?

The categories and tags "came alive" when the things were actually posted -- but the sidebars still not controllable width.

The width of the sidebars is set in the sidebar options. What did you set their width to?

I did that. I tried 200, 250, and 300. It had no effect. But I finally found that I could widen a sidebar by using   in some of the longer links. and then I ditched the other sidebar.

how it looks now
http://anartist.biz/mccall/

I still don't know how to make the top menu of categories drop down to reveal subcategories, which eventually should be 3-tiered.

Categories actually only appear in the sidebar once they have been used, correct? I had made her many more categories and subcategories than show.

You should be able to change the sidebar width. If it isn't changing I suspect there is some code you put in that is preventing it or a plugin conflict. The categories and sub-categories can be implemented via the way they are created or via the WordPress menu builder.