I think you need a google account to access free collab runtimes. If you have one, click here - https://colab.research.google.com/drive/1QBsaDAZv8np29FPbvjf...

Scroll down to prompts and put in your prompt. I just did:

    prompts = ['fire ants attacking a school bus cinematic 35mm']

(re 'cinematic 35mm', you'll find that there are little bumper phrases, like 'in the style of <artist>' or 'trending on artstation' that sort of thematically guide the output)

Click on 'Runtime->Run all' and let the notebook execute it's initialization steps and then start to generate the image. By default it goes 1000 iterations, and spits out what it's working with every 100 iterations. Once you get one you like you can update the prompt, re-run that cell and the one below it to generate something new.

I pay $9/mo to get access to better GPUs (usually P100 sometimes get better), the free accounts tend to get slower ones so it might take 30-60 minutes to complete per image.