There are a number of good sources online you can use to get started. Wikipedia has some good information (https://en.wikipedia.org/wiki/Hangul) and polyglotclub looks like it has a pretty good course (https://polyglotclub.com/help/language-learning-tips/learn-korean-writing).
You can also look for the Talk To Me In Korean site's Hangul book and lesson, this is no free. It's a good book and generally their coursed are well structured, fun and helpful.