Update README.md

Author: sauravhathi

README.md

@@ -17,13 +17,15 @@ This is a simple image generator using [OpenAI API](https://openai.com/api/). yo
 ## How to use
 
 - type a short description of the image or a keyword
-- click on the generate button and wait for the images to load
+- click on the generate button and wait 3-5 seconds for the images to load
 - you will get 3 images generated by the API
 
 ## API Reference
 
 [OpenAI API](https://openai.com/api/)
 
+`Note:` Sign up for an API key and add it to the `api.js` file
+
 ## Run Locally
 
 Clone the project
@@ -34,6 +36,12 @@ Clone the project
 
 Go to the project directory
 
+1. Create api.js file in the root directory and add your API key
+
+```javascript
+  const api = "YOUR_API_KEY";
+```
+
 ```bash
   cd image-generator-openai
 ```