In my two years of experience using R, my first course was at edx, harvard data science, but I had many problems understanding some basic statistical concepts, that was very frustrating.
But I made this course; EDX Data Analysis Essentials, and I could understood many concepts (Z-value, P-Value, Normal Distribution, Modeling and Inference, Decisions trees, Hypothesis testing, and so on). When I finished it, I took again edx, harvard data science, and it wasn´t so difficult understand R functions and playing with the R Studio Console.
Here you are the links:
English is not my native language, but I understood the essential concepts first, and now I work with R, and now it is easy for me associate statistical scripts in R.
I hope this helps. Greetings!
The good new is that you can take a glance in edx courses, before to pay these courses.