Decide which websites to use as your main homeschool guide. Numerous websites will clearly lay out what your homeschooler should learn in each grade. My favorites are Internet4Classrooms and Education. These sites clearly lay out what your homeschooler needs to learn each year and provides links or recommendations for each item.
Choose supplemental websites for your child to use that will help your child further explore each subject. There are websites with educational movies. There are websites with other educational games. There are also websites that deeply explore each subject. For example, AAAmath.com and AAAspell.com are very useful websites. The Discovery Channel for Kids and the History Channel also provide in-depth study resources.
Using the information from your favorite online guide and your supplemental websites, create a checklist detailing the curriculum that you want to cover for the year. You can decide if you want your child to follow a particular order or if they can randomly study and check off subjects at their whim.
Create a computer profile for each child with a custom start page, which you can make using Google or Yahoo. On this start page you can post your child's checklist with links to the exact sites and pages you want them to study. You can also add a series of links that are "just for fun." Of course, these will be educational game sites.
Encourage your child to use the Internet to answer spontaneous questions. When your child asks a random question, do not struggle to answer it yourself (even if you know the answer). Instead go to the Internet promptly and research the question. This will get your child in the habit of using the Internet to learn.