It sounds like you are going full lock one way while entering the corner too fast, causing the car to understeer (go straight on instead of turn). If you imagine yourself in a real car and approaching a corner and you suddenly turned the wheel to its maximum lock as fast as possible, the front tires will not cope and will understeer. It's all about being smooth and make sure you brake well before the corner and in a straight line as possible.
I'd also suggest using a rear wheel drive car to learn because you'll find that a front wheel drive car will tend to "push" wide when accelerating through the corner instead of rotating. And remember to gently apply throttle at corner exit and gradually increase it as you feel the car is straightening up.
I take it you're using a pad which will be harder to be smooth with compared to a wheel, but not impossible.