Collecting the Dung
Use fresh manure from male or female progeny of cow.  Dung can be collected using rubber gloves so that you can pick up the dung without getting any dirt, grass or rocks in it.  Or you can use a clean shovel or similar instrument.  Think good thoughts while collecting the dung, as this heightens its healing effect.
Drying Dung
There are numerous ways to dry dung.  There are also variations in the shape, size and thickness.  One of the more simple ways of drying cow dung is as follows.  Get a simple window or door screen.  The more cow dung you wish to spread the more screens you will need.  They can be bought at used building supply outlets for as little as a dollar a piece.  Place the screen on the ground or a smooth surface like a sheet of plywood.  Then pour the fresh cow dung on the screen and spread it to the desired thickness with a pointing trowel or similar tool.  Next use the pointing trowel to cut the wet dung into nice size pieces.  Lift and dry the screens off the ground for better air flow.  After the dung has dried, in usually about 4 days it can be scraped off the screen in pieces ready for Agnihotra use.
Making Ghee
Ghee can be made from unsalted butter in a electric cooker (called a “crock pot”) or ona stove on very low heat.  The idea is that the butter heats very gently until all the white foam is cooked out and has  risen to the surface.  Whey also separates from the ghee, stays on the bottom of the pan and looks like water.  Ghee is the golden liquid.  The foam that collects on the surface can be spooned off and fed to animals.  When the ghee has turned perfectly clear it is ready, and can be strained through cotton cloth, a coffee filter, or a white paper towel.  Store the ghee in a glass container.  Properly made ghee does not need to be refrigerated.  Ghee becomes even more medicinal as it ages.