B.C.
The best way is to snuggle up with him and read read read to/with him morning, noon and night.
No website is going to be an adequate substitute for your involvement in the process.
My son and I had just about every Dr Seuss book memorized.
Make story time happen just about any time during the day.
Have him look at the pages with you and pick out the letters.
'A' will be one day, 'E' will be another day, etc.
Play games where you get to know one word (like 'car') and then have him find that word anywhere it appears on a page.
What ever you do - make sure it's FUN and not a chore and be patient.
My son had a hard time with it up until the 2nd half of 2nd grade, and then he just took off.
By 3rd grade he was reading Harry Potter on his own - the school librarian couldn't believe it - she had him read the first few pages to her out loud before she let him check out the book.