To use Spell, simply sign up for free and access the platform. You can delegate tasks to autonomous AI agents by selecting from a variety of plugins and customizing their settings. These agents can work on resolving your problems, accomplish goals, and perform various tasks. You can also utilize features like prompt variables, powerful library of curated prompts and templates, and spawn multiple agents to work in parallel. Spell offers a user-friendly interface to interact with the AI agents and facilitate efficient task completion.