I have a requirement where client wants to put images in RTF content by just putting the Image URLs(absolute URLs) and not using Tridion DAM items. I thought of using CK Editor's Image plugin to do the same. After reading so many articles, i am not sure of CK Editor will work for me or not. Also, I am not very sure what all configurations and functions to be used in js file to make the editor's client. And on top of it I don't want to open a second Pop up to fill the content. Will it be possible anyhow?
If you very specific to CK editor, you can refer GUI extension on Paste Special Cross Browser Extension
It will help you understand, how to use, CK editor in Tridion.
As Nick suggests, there is out of the box functionality to add images into rich text fields. If you're not seeing the add image icon in the Ribbon Toolbar it's possible it's been excluded by configuration - see the link here [login required].
If you're seeing the add image icon but are unable to add images through this supported method then please update your question with a use case and ideally any errors/screenshots you can add - remember the more info you give us, the more relevant the help we can offer.