Does anyone have a good clickjacking material to read?

[harryninja]

I want to learn more about clickjacking how this works, i've seen some sites that gives codes exemples, and i also see that this kind of vulnerability can be found but the thing is how do i inject the code into the target site, and that's what i would like to learn, i'll not harm any sites or steal data is just a thing i would like to learn, Thanks a lot.