Homework is something which is meant to be done by the child and not their parents. It is important that parents do provide guidance though as this can make a big difference.
In primary school, homework will be easy and at a level that parents can do. It is tempting to do it for them, but it is important to make sure that you do not. The teacher will know that you have done it and they will not gain anything from you doing it for them. However, it is important that you make sure that you get your child to do the homework, that you make sure that they are concentrating and getting on with it. You will also be expected to read with them on a daily basis and you will need to listen to them read and make sure that you are teaching them to sound out the words correctly. It can be useful to get a book to help you with this or ask school about it because you want to be sure that you are doing it properly.
As your child gets older, they will get a lot of homework and there may be quite a lot of it that you will not be able to help them with. In this case it is important that you still show an interest and make sure that they are getting it all done. You need to check it every so often, just to see whether it looks like they are putting in the right amount of effort. The best help that you can give is to teach them time management skills and make sure that they get things done on time. If you have always made sure they got their homework done on time, then hopefully they will already understand the importance of doing so. It is also worth checking if they are getting their homework right as you may need to talk to their teacher if they do not seem to be understanding what they are doing properly.