Where is the oil pressure sensor located?

I got the vehicle pre-owned. Oil light has flashed on and off since I got it 2 years ago and the check engine light has always been on, but it ran fine until last summer. Last summer I stopped at a red light and the vehicle shut off. I finally got it restarted, and it shut off again about 1 mile down the road with all the oil and coolants pouring out the bottom of the car. I refilled those (I was in a diff city than I live). After it cooled down, I drove it back home where the oil and coolant I had just put in all drained out again. I have had someone look at it, and they replaced a few things and that did not work. The car will now start but automatically shuts back off after about 20 seconds or so. It is full of oil and coolant (also has a new battery) so I was told to replace the oil sensor. I have that, however I don't know where to put it. I can't find the one that is in the car right now. I have watched YouTube videos and Googled, they all seem to show something else. Please help just basically explain how I locate it. I'm a single mom and I have no one to help me.