Oh I understand, yes being socially skilled is highly valued in our society. I would say there are no text books to teach us how but of course there are, whether they help or not is another matter.

Your instinct that he walked away because you were awkward may or may not be true (always tricky to assume what goes on in others heads), but if you were right that makes him a rather impatient person.

Social skills are such a broad topic, I can tell you what my techniques are - my fallback plan is always to show an interest in the person I am talking to. Most people love talking about themselves so I have found this works quite well - they don't seem bothered I'm not cracking jokes (I have humour but usually only with those I'm close to).

Treating the whole social behaviour scene around you as an experiment or a game may be one way to tackle it. Watch, observe, mirror (another good technique). You are a bright and able man who I believe can turn his mind to anything. Don't be discouraged by any mistakes, try to treat them as a learning curve, be kind to yourself, start small (serving staff in cafes can be good place to experiment as those interactions are of no real consequence)

You did not grow up with good role models for social interactions, your parents were unable to teach you that. But you can learn your own ways - this will be just you, you may have to battle inner voices which try to deter you and overriding those will also be a challenge, remember progress may be small but it is always worth celebrating small victories. I am rooting for you.