What verse in the Bible does it says a man should not wear women garments?
Deut 22:5 "A woman must not put on the clothing of a man, nor should a man wear the clothing of a woman. For anyone doing so is detestable to Jehovah your God."
For an Israelite:
This law was put forth to the Israelites for the purpose of deterring the Jews from leaning toward homosexuality, as the other nations were practicing. Although both men and women then wore robe-like garments, there was a difference between the garb of males and that of females. Similarly, in some parts of the earth today, both men and women wear skirts and slacks, though the styles differ for each sex.
How this applies to Christians:
God's Law to the Jews gives us insight as to God's thinking on the matter. This is backed up with the principle found at 1 Timothy 2:9,10 which counsels women to "adorn themselves in well-arranged dress, with modesty and good judgment; sensibleness." This principle applies to both male and female.