Not sure if this is in the WA training but, I went ahead on my own cause I was so anxious to do it on my website, so I went and did my research. There's a training here in WA on inserting banners on the sidebar, you can always check it out and get the idea. Just found an easy way to add my own image.
There was ways online showing me how to do it but, for some reason It didn't show where and how they were getting the text/code for the picture that they're putting on sidebar. Here's what I did.
1. open a new page
2. put a picture that you want to add on sidebar on that new page (by the way, I'm using text on sidebar widgets)
3. once you put the image that you want, click text and copy the whole code.
4. go to appearance and open widgets
5. click on the text you want to place the image in.
6. just paste the code on the text and save
When you check your website your image should appear on the sidebar. You can always adjust the image on the page you created it in and copy that code and paste on the text. When you're done inserting the image on your sidebar, you can always delete that page you created for that project. Here's the link of Kyle's training so you'll have a better idea on what I'm talking about. https://my.wealthyaffiliate.com/training/adding-a-wa-banner-to-a-wordpress-sidebar-widget
Hope this helps any new member in WA who wants to get creative in there website. If you have any questions feel free to ask.