Is there anything you want to do in particular? I'm currently going through a learning process (coming from knowledge of SQL) of OOP and depending on what you want to do, there's better resources for one thing over anotehr IMO. If you want to make games for example, then a course for learing c# or python by making 2d games would be better than a course for MVC to build a website with a database underneath it.
If it's just groundwork concepts of class, methods and objects then any course thats based on a language will cover these.
Personally I'm doing a couple of Udemy courses that have things to "make" as projects, which is a better approach for the way I learn, which is by doing.
Not really, I am web developer (using HTML/CSS/Javascript & ColdFusion{And I'm at that stage where I want to start getting better and working with Javascript a lot more}) but I've always wanted to know what these fundamental concepts/ideas (are they computer science fundamentals or design fundamentals etc) are that people always seem to mention but never say what resources to look at.