Chatbots Tutorials or help?

I'm looking to add a chatbot to my website.

Can anyone recommend, tutorial, which bots to use or avoid (preferably free) and anything else I might need to get implementation right?

Edit: I'm thinking it might be better to NOT have as part of my social media account (like facebook messenger with a bot) but I'm not sure. I'm starting from scratch.

Thanks!

Shameless bump