Self service

I went to a gas station nearby my house. The gas station was self service. I stopped my car and I was in trouble right after. It was my first time to go to a self service gas station. At first I opened the lid to the gas tank and then there was another cap. I tried to open the cap but I couldn't. I was trying to open the cap for 3 to 4 minutes, then a service staff approached me. He asked me "May I help you?". I answered him " I can't open the cap". He was able to open it and he asked me again "Do you need anything else?" I asked him how to pour gasoline into the tank and how to pay. He kindly taught me how to do those things. I had everything done by the staff. It wasn't self service.