Can Campaign Monitor support an email which consists of only png and jpg images + plain text and doesnt include any html. How to upload the images?
You'll always need some form of HTML when creating emails, whether they have images or not. If you don't have the knowledge then you can work off the existing templates Campaign Monitor has provided as a starting point.
Uploading images can be done via the WSYWIG editor - you'll need to have a campaign created off a template to achieve this.
Obviously there's more to tell within the gaps, but your question is very general and you ought to be more specific.