As @jack randall said you, it’s compulsory to upload the new version of WordPress in order to upgrade the files. After that, you will choose the correct images in the gallery of your account. And then, waits the media’s downloading ! Don’t hesitate to inform us if it doesn’t work like this…
In my mind, maybe it will be better to choose a new theme in order to keep your products in their own page in your blog.
If you upload a new template, there is a risk to lose your porduct’s form…
