hi friends,
I learnt Spoken English in a British Accent which is very different form US Accent. now i want to learn US accent how can I learn it.
It depends on which accent you would like to learn. The people in south Texas speak differently from the people in Maine. The drawn-out speech of people from Alabama is quite different from the quick-speaking people of New Hampshire. When televison first became popular in the US, many television stations had to arrange classes to teach their news reporters how to speak so that a nationwide audience could understand them. What you hear on American television is basically a midwestern form of English. You might be able to listen to the Public Broadcasting System (PBS) on the Internet. Staff members of PBS are generally required to speak formal English - though it will lack the local flavor that you would hear if you were actually in a certain area.
As I had responded to a similar inquiry some time ago, be careful what you wish for. As I wrote also, would you like the New York, Eastern, New England, Mid-western, Southern, South-western, Lake Region or (maybe 2 or 3 other) U. S. accents? Native language accents can be attractive. It would be better to concentrate on pronunciation rather than to try to assume an accent that is not natural.
Just a tip about something I noticed in your post: in American English, typically we use spelled and learned instead of spelt and learnt.
Spelt and learnt aren't wrong in American English, but to most speakers they sound very British.
Most American television and movies will feature a "neutral" American accent, even if the people living in the location where the movie takes place would have an accent. For example, on the show Friends, they all generally speak with a neutral American accent, even though the show takes place in New York City (which does have a strong regional accent).