The two tips are supposed to be for high (yellow green) or low (purple) water pressure. Try filling it about 3/4 full with warm water, then add 3-4 ounces of CS. Close the lid, swirl it around, and spray. Once done, pour any remaining soapy water from the gun into your wash bucket so you don't waste it. Sure, you can start with 1/3 full...I guess that would be about 1-2 ounces of CS?
Remember, you won't get thick, foamy suds like the Foam Canon. It's just not made to do that.