You cannot make calendula essential oil. The plant does that - it is the 'essence' of the plant. The thing you want to do is to extract it - from the petals, and you'll need specialised, very expensive equipment to do it. You could hunt around the internet, if you're that interested!

You can, however, make an INFUSED oil.

Pack a jar with fresh herb and pour in enough olive oil to completely cover. Leave on a sunny window sill for 2-6 weeks. Strain liquid into another jar through a fine cloth or coffee filter, seal and label bottles. Use as a massage oil or add to creams and lotions. Do not ingest.
OR
Heat about 280g dried herb or 800g fresh herb in about 700ml oil in a double boiler for 2-3 hours. Strain off the solid matter. Do not ingest.

If you soak a herb in water, you're making a tea - either an infusion (pour boiling water over leaves or flowers), or a decoction (boil the herb - roots, bark, stems - in water).

I think the woman you refer to doesn't know oil from water.

Thanks for the information. I thought it was strange that she called it oil and then said it was made with water. I'm glad I asked here.