First Time Yeast Starter Question.

Ive got my first yeast starter going. 4 to 1 water to DME. Its going great in my cooler set to 52 degrees for Lagering. The starter has settled into 3 layers. Ive seen other posts about decanting or pouring off the beer before pitching. Can someone explain this. Do I pitch the entire contents of the beaker? Or do I pour off the top layer and only pitch what looks like a small yeast cake on the bottom?

Thanks in advance!

You can do either and be fine. Some decant and some don't. I don't just because I don't feel like cold crashing it and waiting. Unless you are making a 2+ L starter there is no real need to decant.

After 2-3 days of growth, cold crash the starter by placing in the refrigerator overnight. This will drop the yeast out of suspension and leave you with clear wort atop a thick cake of yeast. Just before you begin brewing, remove the starter gently from the refrigerator and place on the counter. When your boiling wort has cooled to the appropriate temperature, and it is well-aerated, gently decant and discard about 90% of the clear wort in your sink, being careful to leave some behind for swirling to make a slurry with the yeast cake on the bottom. Pitch that slurry into your aerated wort.