Sure, a BA is 4 years in the US, but that doesn't mean they don't recognise a BA from another country just because it's 3. What kind of year-long course are you talking about? You can't just add another year to your existing BA.

i means any yearly course like post graduate diploma in management or any other yearly course .
i know that i cant add 4th year . but i can add another yearly course.
so i wann to know about a yearly course which are eligable for full time mba

If you've already got a 3 year BA and a few years' work experience, I reckon you'll be ok as you are. Of course it depends on where you're applying and what they specify. Which places are you looking at?

thanx for your info.
i am looking at taxas
i wann to go good universities in texas

and
i have no work experience
that`s why i wann to go for yearly course

Another thing to consider is that you may need some preparation to meet the minimum TOEFL requirements. Some schools offer acceptance to applicants who score below the minimum TOEFL requirements on the condition that they participate in an English language course.

A couple more things you might want to take a look at and have a think about:

http://www.find-mba.com/texas

http://www.find-mba.com/board/5921

http://www.find-mba.com/board/2338 At the bottom of this discussion there's a link to an article on US schools which don't require a GMAT test score.

And lastly, http://www.find-mba.com/board/6336 Heed a_mukerjee's words, for she's not only a stalwart of the board, but wise also.

And that's it, I'm afraid. You'll have to do some digging yourself.