Teach your child the basic sounds involved in reading, beginning with the alphabet. You can do this either online or using a simple book. Ensure that your child is familiar with the alphabet sounds before proceeding.
Choose a book suitable for his age group and reading ability to read online. Sites such as 2020, Magic Keys and PBS Kids (see Resources), all have books available free online.
Read through the online books with your child, either reading out loud yourself or having the child read to you. If you are reading, ask your child questions at the end of each page about the story or the pictures displayed. This will give an indication of whether he understands the text or not.
Help your child with difficult words, and teach him to sound out words which are long. If your child is new to reading, zoom the screen in to make the words bigger. Tell him to trace the words with his finger, which will help him to pace his reading. Don't put pressure on him to read faster, since this will lead him to make mistakes and not enjoy reading.
Stop reading 30 minutes before bedtime, since staring at a computer screen can damage your body's sleep patterns (see References). Put the child to bed, and talk to him about what you have read, and about what he likes about the book. This will develop critical-thinking ability, which is a strong foundation for a young reader.