oh, I think may be he didn't know that for Japanese there is no difference between /r/ and/l/ in pronunciation. As you don't have phoneme /l/ you can't differ between /l/ and /r/. As a Japanese when I am talking to you I should bear in my mind that I am talking to sb who has only one Phoneme /r/ for both /l/ and /r/. So it is not your fault my friend. For your convenience i will tell you that /l/ is pronounced this way: put the tip of your tongue behind the alveolarage and pronounce /l/. for /r/ your tip of tongue is not touching the alveolarage(behind your teeth). if you give me your email i will send you a software to pronounce you all IPA phonemes. Good Luck yours hiva

There are a number of ways to pronounce R (it depends on regional preference), but the common idea is that R is "liquid", ie. it's a consonant, but in practice, it can almost act as a vowel. There are a number of youtube videos on pronouncing R; they're all by American presenters, so I'll add that my own R is very relaxed, and in the same position as F/V. For me, my R is nowhere near my L.