I think you need to slow down a bit...relax, have a homebrew.
After you've racked your beer, swirl the primary a bit to mix the remaining beer with the yeast cake on the bottom. Break it up really well.
Depending how much you want to save, use 1 or 2 growlers. Pour about 1/2 gal of trub into a sanitized growler. Add about 2 C of sterilized water into the growler and swirl some more.
After about 10 minutes or so most of the trub will settle out. Pour off the liquid into another sanitized growler. (Re-sanitize the original growler so you can use it again).
The "muddy water" is your yeast in suspension. You need to seperate the gunk from your yeast. This is the whole purpose of the experiment.
Wait another 10-30 minutes and observe if any more garbage has fallen out. If so, pour off the liquid into aother growler (the 1st one again).
At this point you can put it in the fridge. The coldness along with time will allow the yeast to fall out of suspension.
Prior to use you can either pour off most of the remaining liquid leaving only yeast behind. You can add 1 C of cooled sterilized water to remix the yeast
for your starter.
I like to keep mine out of the fridge because I like repeating this process until I have clean yeast. This may be considered overkill by many, so it's not necessary.