As far as I know, the actual trained system is proprietary, and you can only use it by requesting access to their online system for generating imagery: https://openai.com/dall-e-2/

There are open-source efforts to implement it and make trained models available, but I don't imagine they are yet at the same scale of ingested data / model size as OpenAI's system: https://github.com/lucidrains/DALLE2-pytorch

Not Dalle2 specifically, it's proprietary and there's a waitlist. Older open source alternatives include https://huggingface.co/dalle-mini