Changing Block Sizes

I was wondering how to change block sizes. I read in some of the Index material that there should be "sliders" available when scrolling over a block, but I don't see any sliders when I scroll over the block I wish to change. The block that I wish to change is a sitewide block - does that make a difference?
I am using the Superhero theme, if the theme makes a difference in changing block sizes.
Thank you!

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Adreco replied on at Permalink Reply
In edit mode, select the block area and choose "add Layout" to edit block area columns.
In Super Hero, I do not think the sitewide block areas can be changed this way but the others can be.