I believe the best way to learn any programming language is learning by practice.
The first step is to read the elementary of wolfram language with the help of following book:
https://www.amazon.com/Elementary-Introduction-Wolfram-Language/dp/1944183000
Then I suggest you to find your mathematical related interests, like data analysis, statistics, machine learning, etc. Trying to get to know more about the topic by doing related programming works with wolfram language, and you will have a better idea on APIs, techniques from wolfram language. Actually when I was a student, many of us were proficient in wolfram language because we were used to solve math and calculation problems by Mathematica ;)
If you are just interested in wolfram language itself, you can browse the posts here in the community with "staff-picks". Many posters use wolfram language to analyze practical problems, which are fun and you will be attracted by them. Certainly, community is your best friend and if you have any question, you can come here and ask for help.