If you spilled engine oil on your engine you should use a paper towel or rag and wipe up as much of the engine oil as you can.
Then use some engine degreaser spray and spray the area where the oil spilled on the engine.
Then let it sit on the engine oil spill for a few minutes and then use your garden hose to wash the degreaser and engine oil off the engine.
Then let the engine dry off before starting it.
You can also use some Easy Off Oven Cleaner to clean the engine oil spill off the engine or use some dawn dish soap or Purple Power Degreaser.