It's just motor oil. So normally when you change the oil the filter, the filter seal gets oil on the seal.
1. Check the oil filter and see if it's just loose.
2. If the filter is tight, remove it (turn counter clockwise). Pug a rag under the filter, it will leak oil. Check the seal on the oil filter for any gouges. Make sure the surface on the engine block is clean and free of dirt.
3. Get some clean oil. Put some on your finger, then apply oil to the oil filter and replace. Hand tighten and check for leaks
Since it just started, did you just get a oil change ?