This is a nice article from http://theoptionsinsider.com - Josip Causic which talks about the butterfly spread and using the TradeStation software platform. If you're not familiar with the Butterfly spread, this article has a nice graph which instantly illustrates the meaning of the term.

Josip talks about using the TradeStation Option Analysis Window and gives many more details on this subject.

Butterfly: Part II
This exposé, the second in a series of articles on the topic of Butterfly spreads, will visually show how to place a Call Butterfly spread using the TradeStation platform. The actual trade is NOT meant to be a trade suggestion.

The first of many figures below shows the daily chart of the underlying on which a Butterfly Call spread will be placed. Observe that the underlying has closed at 42.55 and that I am anticipating it to stay range-bound between the 45 level and the 41 level. Whether that will happen remains to be seen, yet for educational purposes only, let us go along with the assumption that the underlying most likely will be by Feb 2010 expiry somewhere close to the 43 level.
http://www.theoptionsinsider.com/education/?id=3757