Yup, you'll have a fir bit to concentrate on, but when he/she/heshe says keep your weight on your front foot, keep your weight on your front foot!
It's tricky, because if you're feeling cautious/scared, it's natural to lean back, but that's when you WILL fall over!
Weight over the front foot = easy turning, more confidence, upwards spiral of fun, improvement and good times.
Weight over the back foot = difficult turning, falls, downwards spiral of hurty wrists and bum, fear, more leaning back and bad times.
Other than that, if something isn't working and you're getting frustrated, try and clear your mind of everything you think you're doing and try and follow exactly, as if for the first time, what the instructor's demonstrating.