Was offered a free trial but wasn't free.

I clicked a button offering a free trial via the website. However, I have been charged $39.99 immediately even though it was a 7-day trial. When I cancelled online, there was no mention of the free trial, just a discontinuation of the automated payment. This process was very confusing and I feel deceiving. How do I get a refund of my money. I had a membership for about 10 mins. Account name is geoffdarst