I purchased a electric steam iron from UK ( 230 V) how do I get it to
work in USA (110 V) ?

You require a 110V > 240V step-up transformer which is adequately
rated for the iron, which may be in excess of 1,200 W. One UK supplier
of what you want is
http://www.threedoubleyou.com/convertpower.htm
and you would be looking at spending about GBP 100.

I understand that American kitchens often have 220V sockets for
washing machines etc.; this would be suitable provided it will supply
enough current for the iron,m and the iron is protected by a 13A or
15A fuse or circuit breaker, either in the plug or (if you fit an
unfused American plug) the supply panel.

BTW, if you've lost the instruction manual, the UK wire colours are:
brown - live (hot)
blue - neutral (cold)
green/yellow stripe - earth (ground).

If the appliance has a 3 wire flex, the appliance *must* be earthed (grounded).

Owain

All us homes/businesses have 220VAC available. Have an electrician
install an outlet for you and install the appropriate connector on the
iron. With a dedicated outlet there's no need for a convertor and no
worries about overloading a convertor convertors (just a simple
transformer) are regularly available as well. We run an italian
esspresso machine on one here and I have several for testing other
equipment. If you'd rather go with the convertor Todd Systams will
have just about anything you'd need.

http://www.toddsystems.com/home.html

It could be cheaper to buy a 110V iron, maybe cheaper than a
transformer, and certainly cheaper than any electrical work.