How to use "however"?

"We were supposed to go to the dance last night, however, it was cancelled because of lack of interest." This is INCORRECT.

A semicolon, rather than a comma, should be used to link these two complete sentences:
* "We were supposed to go to the dance last night; however, it was cancelled because of lack of interest." This is CORRECT.

It should be noted that there ARE situations in which you can use a comma instead of a semi-colon:
* "The match at Wimbledon, however, continued despite the bad weather." This is CORRECT.

There is only one complete sentence in this example. It is not a compound sentence.

Source : http://www3.telus.net