The W3 school provides lessons on how to use Bard Ai (now called Gemini).  The lessons are broken down into simple exercises for you to follow, providing beginners with everything they need to get started.  

The lessons includes: -  

• How to sign up 

• Setting roleplay prompts 

• Few shot prompts 

• Using Gemini to brainstorm 

• Generating documents with Gemini 

• Gemini social media 

Link: Gemini AI lessons 

Source credibility:  

The W3 school is a free resource and tutorial site that provides coding and software tutorials.