Where do you sit in the class? How big is the class? If sit you closer to the front, you might not be distracted by seeing the other students. Just answer the teacher as if you two were having a conversation. Do you know your classmates? Make friends or even just be acquaintances with them and sit next to them. You might feel more like you are talking among friends than answering in front of a group. Give yourself a goal. Raise your hand at least one time a week. Then once every other class. Then once a class. Raise your hand straight up, not with a bent elbow. It can be hard for teachers to see the bent-elbow raised hand. Listen to the other students. You will see that a some students make mistakes or don't know what they are talking about and just want to talk to hear themselves talk. You can contribute your good ideas / answers for the benefit of the class. Talk with the teacher and let him/her know that you feel nervous, but that you enjoy the class and the material. Tell her you plan to speak up more. Remember that since you are taking the the class, you want to do well and you have just as much a reason and right to speak up as any other student. It will become easier as you become more confident.

You throw the hap over the wall, and you jump over the wall.

Don't think too much about the possible subsequent awkawrdness, the more you care about it, the less courage you'll get.... And tell yourself that you don't need to win any compliment, you just contribute your opinion, it's the most common thing to a student. No big deal. Being a student, you have the right to make mistakes.. Once you take the first step, you'll do better and better...

Just talk. First with peoples and teachers on iTalki. Then with your fellows at the university. Then catch one old American women in nearest airport and sell her ten pens. I suppose that your problem is not in English (do you talk good, when you talk with yourself?), but in the modesty, shyness. It’s my problem too. And I try fight. Is it hard? May be, but it is funny too. Sorry for my issues, and good luck.

Just do it! It will get easy the more you do it.