I know that front brakes control the front wheel and rear brakes the rear wheel. However, I remember in the MSF course that I should only use rear brake before making a tight, slow turn, and never the front brakes. In addition, I should also use rear brake when stopping from a high speed, and not so much the front brakes. My question is, when is the appropriate time to use each brake when riding? I would love an explanation.
The MSF course is designed for complete beginners and often has idiots teaching it. Braking is different with different bikes. Is it a cruiser, sport bike or something else that you are riding?
Don't be scared of using them both but you need to use them progressively and don't just stand on the foot brake and a fist full of the front brake; that will certainly bring you down for a close look at the bitumen. I am assuming you are road riding but you haven't said the make and model. Most bikes when braking fairly hard the is about 80% of the braking force on the front and 20% on the rear wheel. If you try to get too much from the rear brake it will lock the wheel and you will be in a skid. With the bike upright apply the front brake using the 3 fingers from the thumb, the front of the bike will dive down and you will loose speed. I would get a bit used to the front brake for upright braking then start applying more pressure and bring on some back brake gently. Then work them both progressively from about 40 mph each time till you are happy with the braking rate and used to the bike dropping her nose; and that is very normal. If the road is wet or dirty brake earlier and with less pressure; if you ever feel a shudder or the back wheel moving around ease off the brakes. Ease the brakes a bit when you are below 10 mph. Once you have confidence that you have a good feel for the brakes you could try using the brakes when you need to reduce a bit of speed leaning into a corner; the same amount of pressure when the bike is on less or the same lean as it would be with you sitting on it with the side stand down; if you need to brake with more lean use less pressure. I can't give you more advise not knowing the make and model of your bike.
For most long stops ill use a bit of both brakes. for short stops and turns i use the front brake. Also never slam a motorcycle's breaks like a cars or you'll fly like a rag doll.
easy use rear for high speed slowing down but down slam on it or else you'll go flying. slow speed to add friction is the front brake. never use the front brake on high speeds or else you'll end up in the hospital. hope this helps high speed-rear slow speed-front