First lay out your tarp in an area where grass is thick and soft.. Make sure there are no rocks because that will hurt later
Peg the tarp down with the pegs angled away from the tarp. Put them in deep so they don't poke out of the ground. Use a hammer of needed.
Hook up the hose splitter and attach the two hose to it at the end of one hose attach the sprinkler & place at the middle edge angled towards the tarp to get a lot of coverage
Place the other hose end where you are going to start your slide
Turn on the water and put a little soap everywhere and mix it around with your feet.