@ced1213 The easiest way to put an image in a text widget is to open a new post and put it into the new post editor in the usual way, using the visual editor. Then put below the image the link that you want the image to open to. Then when you have the image the size you want it, click on the post's HTML tab and copy and paste the code from the post into the text widget and save it.
You don't need to save the post, but if you're likely to want to go back to the HTML to edit it for the text widget (in case it doesn't appear the way you'd expected it to), save it as a draft so that it won't be seen by anyone other than you, then get back to it via the 'Posts - all posts' in your dashboard's side panel.
As Timethief says, you need to find out the width of the sidebar (and footer) areas for the theme you're using.
By the way, I second what Timethief says - you might do better with the Imbalance 2 theme. It's the one I use for my artwork so, if you want to see what it looks like in action, you can clickk my username - or go to the showcase to look at it. The images that show on the homepage in Imbalance 2, need to have the featured image activated in each post.