I realized that when I tried to wean my son at about that age that it is actually a very difficult time to wean. Children are going through so many developmental changes already, that changing the one comfort they have always known is difficult. I have to admit that I gave up, and nursed another full year.
Still, as many mothers say, even if you nurse into a second year, it's time to change it onto your terms, instead of your infant's. So, the first place to start is by changing some of your child's habits. Help him learn to fall asleep separately from nursing, that is a first step. Weaning a child that relies on nursing to fall asleep is very difficult, so if you can remove that barrier, it will help. I am sorry that I have trouble remembering HOW to do this, however. I just know that the connection between sleep and nursing is what is most likely to make an attempt to wean traumatic.
Second, gradually replace the daytime feedings. This should be relatively easy, since while awake infants are eager to explore and learn, and can be distracted. I actually weaned days off with both my children first because it is relatively easy. But, I believe that may have made finishing the process more difficult.
I have to confess that weaning my second child, at age 2, was so difficult we took the "trip away" alternative. I had never been able to disassociate nursing and sleep with her, probably in large part because I lacked the will, since we knew this was our last child. Anyway, in order to wean her from nights, I LEFT for 4 days. She had no choice but to learn to asleep without nursing, and she had been prepared by being told mommy's milk was doing away and there wouldn't be any when mommy came back.
Hopefully the books in the post below will have more recommendations, but I think in the end what I recommend most is making sure that your heart is in whatever process you choose. Our little ones have our number when we're emotionally conflicted, so being confident in your decisions is very important. Do what is right for you and your children, and not what you think you should do, and you will be fine.