Know-How Exchange : Advertising/PR

You'll need to imagine someone reading your ad and considering if this is something they'd be interested in and if it's worth their money. If you've sold these courses already, then you might understand why someone bought them. If this is new to you, then then you need to figure our exactly who would buy it. It's not about the right photo or appearance in general. It's about the words, the offer, the value of what you're selling, where the ad will be shown, etc.

You must discover what your potential customers want...THEY may not have words to actually describe it. That is where YOU must provide the "secret sauce" to develop a business to successfully solve their problems.
For a good start, check-out other businesses in the same field, the leader(s) are probably doing some things worth considering. Figure out how to talk WITH as many potential customers as you can - How do they think about their stress issues? What words do they use? What do they ask for? etc.
As you become closer and closer to being an expert, all these questions get better answers.

Who is your primary target audience? Where? What's important to them? What do they do now?

What compelling and unique benefit will they experience if they become your customer?