Dear Mustafa,

First off I would see the video tutorials on CONN, which are very helpful for a quickstart:

https://sites.google.com/view/conn/tutor...

Then the CONN manual (provided along with the CONN archive) can be of great help, although I agree that just like the tutorials the focus is more on the practice than the theory.

For the theory, I found the following book to be an excellent compilation of the current state-of-the-art on functional MRI, which I unfortunately discovered only after developing my own experience with fmri, and it could have saved me many hours: Poldrack, R. A., Mumford, J. A., & Nichols, T. E. (2011). Handbook of functional MRI data analysis. Cambridge University Press. The freely available COBIDAS report can also be of very good use, it's kind of a summary of the book above (of course it will miss information but this is a good read anyway).

Finally, the Andrew Jahn's blog and Youtube channel (for practice) as well as Jeanette Mumford's Youtube channel (for statistical theory) might be very helpful as they are amazing (and free!) resources.

Then as a bonus there are lots of online resources where you can find specific bits of knowledge, but you will need some experience to find out what is pertinent for your experiments (SPM mailing list, http://imaging.mrc-cbu.cam.ac.uk/imaging... etc).

Hope this helps,
Stephen