The best way to become a good reader is to read. Read everything around you, including signs, road names, and posters. To help you learn new words, keep a little notebook and write down new words that you don't understand. Ask your parents, teacher or a friend what they mean, or get help to look them up in a dictionary. (Try WordCentral.com or the Little Explorers Picture Dictionary at Enchanted Learning.)
Start with your A,B,C's and work your way up to Advanced Reader on the Starfall website.
You can practice your alphabet, learn to read and write, work with shapes, numbers and more on the Literacy Center Education Network's Play and Learn site.
Have fun and practice your reading skills at CBeebies Story Circle (from BBC UK).