I would recommend that you find a course at a local community college. Most CC's offer a basic and intermediate course in C++. I feel this is best avenue to learn because it provides you with a good text and an instructor to give you proper answers to your questions. Most importantly the course has milestones in the form of projects that test you abilities. The downsides of this route are time and financial investment. To complete the full C++ section from beginner to intermediate will take 36 weeks. The cost will likely be around 1000 dollars for the semester if you are not eligible for grants.
The second method I would recommend is the home study method. Find a recommended C++ text. Please do not purchase a standard textbook as they are geared toward guided instruction in an academic environment. Make sure the book your purchase is geared toward self learning. I have not much experience with his kind of book as I learned C++ in college, but I will make a few recommendations. C++ Primer, I often hear recommended as if it is a Holy Grail of beginner texts. Beginning C++ Game Programming, I have this book personally, whenever I had trouble grasping a concept in school I could turn to this book for an ultra simple explanation that gave me a hook into the greater wealth of information in my academic text and my instructors lectures.
In the event that you choose the self study approach. I recommend that you not only complete all the projects at the end of the chapters, but that you also conceptualize in your mind some non-trivial project of modest size that you would like to write. A simple text-based choose your own adventure is a good start. As your progress through the book add something of what you learned to your program. There will be a few key points in your learning experience where your project will need to re-written. The first is when you learn functions the likely second is when OOP is introduced.
Lastly, for any self learner, find a good forum (like this one) with friendly helpful people and ask questions. Don't be afraid to be wrong present the issue to the best of your understanding, show your code and accept the constructive criticism of the group. If you follow this diligently you will progress rapidly and gain a strong understanding of C++.