You're going to be making a thick porridge. That's the mash. Stir it well so there are no clumps, cover it and leave it alone for at least 30 minutes. I use a paint-strainer bag for this in an old - and I mean OLD - enameled cooler, like an Igloo cooler from the 1950s (it's called an Artic Boy and I got it for free from my dad, stop laughing). You can do it in another, smaller stockpot (by "smaller" I mean 10-15 quart) using the paint strainer bag.
Check out Deathbrewer's stovetop partial mash tutorial here
. It's easy!