You can easily add an image to a text widget in your sidebar.  Here’s how you do it:

-Create your image: It is best to create this to the dimensions that you want the picture.  A sidebar is typically 300px wide so you do not want it to be bigger than that.
-Go to any post or page and open it up.   At the top of the content area you will see “upload/insert” and a little gray box next to it. Click on this box and upload your picture.
-Scroll down to where it says: “link url” then click “file url”and copy that url.
-Close the post and go to “appearances” and then “widgets.”
-Drag the text widget from the left side to the sidebar area that you want it in on the right side.
-Enter the following code, pasting in the “file url” you previously copied where it says “add your image file url here.”

The Code
-To insert a picture only with no hyperlink add the following code:
<img src=”add your image file url here.”/>

-To insert a picture that goes to another link when it is clicked on (hyperlink) add the following code:
<a href=”add the link here that you want people to go to when they click on the picture”><img src=”add your image file url here.”/></a>

That’s it!