Some people are academic naturals but some of us have to work extraordinarily hard to accomplish even the measliest of tasks. Sadly I'm one of the second type. For me, computers come naturally but ask me to write a paper and I'm totally screwed. The difference is that I'm quite different from other people. I have a learning disability as well as ADD and can't tell you that trying incredibly hard without a real result really sucks but don't let it get you down.
Step 1: Do your homework
This is one of the most important tasks. Doing your homework is a must because it takes what you learn in class and gives you a platform to build on the following day. If you do not complete your homework, you will not have the same platform to build on and, over time, your metaphorical bridge will collapse because you do not have the needed building blocks in which to reference from. Homework isn't just given to students by teachers because they feel like it (well in some cases it is :) ) but rather to help you later on in your learning.
If you have a problem with a specific task, try asking for help in the end of class or in an email. Many times your teacher can help you a lot more than a parent could because the teacher knows exactly where the class is and what some common problems are. A parent, although trying to be helpful, may not be very good at helping because they are at a much different education level and therefore know things that will really mess you up.
One of the tricks to completing homework is dynamic time management. This means that instead of doing exactly what the teacher tells you to do, only do the stuff you have a problem with. An great example of this is math homework because quite often you will receive a large number of questions that may be deterring. What helps is to only do the things that you have a problem actually doing rather then every single question. This is a much more effective homework strategy because it gives you the time needed to work on everything else that you may have a problem with.