I’ve recently started learning R again, picking up where I left off last year. It’s an introductory course (three afternoons) for PhD students and other faculty, organized through the Kurt Lewin Institute. Here are a few online resources that I found especially helpful and accessible for a beginner. These are free, friendly, online self-paced introductory courses on using R/RStudio. I did them about half a year ago in my spare time/weekends and really enjoyed myself.
Try R by Codeschool
Introduction to statistics by Datacamp
Introduction to R data science by edX