Before/After preamp

I've been reading around on the net about setups and so on. Something I keep noticing is putting an effect before or after the preamp. How do I do this? What does it do?

Also, I noticed a review on Slash, which said he put his EQ through the FX loop. Does this make the EQ more noticeable/better sounding?

http://www.amptone.com/truesecretofamptone.htm

This is the website where I see most of this being talked about.

It's agreed that some effects sound nicer before the preamp and others should be connected after .
For example , most people prefere the wah connected the first thing after the guitar, which makes it before the preamp.

The EQ thing is pretty arguable , some people like it before , others like to put it after the preamp , and others use 2 EQ's, before and after the preamp .

So, after the preamp would be going through the FX Loop?

Yeah , when you connect something to the FX loop , it's between the preamp and the power amp.