I just started my DS (7months) with some yogurt for "breakfast" --did a lot of research and read that it's one of the only dairy products that's actually encouraged to give to babies. I was hesitant at first too
I buy the Organic YoBaby Plain Yogurt--He didn't like it at first either but I mix it with mashed banana and some cooked brown rice and now he LOVES it! Same advice as Sprocket; Try mixing in some applesauce or other steamed/puréed fruits
Also, I have used the Udi's infant probiotics any time he is on antibiotics or if we are traveling away from home--you can try that as well if all else fails with the yogurt!
Good luck!