Welcome. I am sorry to hear of your misadventure.
The best way to learn quickly is to go to the New Mystery Shoppers area of the forum and read, read, read, the top dozen or so topics that are "pinned" to the top of the topic list. Then, us the list of companies found at the bottom of each page to start signing up with legitimate companies. You can use the forum to look for what other shoppers have to say about each company. Real MS companies never pay in advance and do not ask you to send large sums of money AND do not pay much for each assignment. YOU have to apply for a job with a real MS company; they will not just assign it out of the blue!
Good luck. We are here to help.
Based in MD, near DC
Shopping from the Carolinas to New York
Have video cam; will travel
Poor customer service? Don't get mad; get video.