If you want a direct answer give us the exact question you want answered. I cannot believe that 'who were the Turks?' is a question set by a teacher. Here's a link to be going on with:
http://www.eyewitness...tory.com/crusades.htm
In case you can't be bothered reading it, it tells you that the Turks took over large parts of the Middle East in the late 11th century and took Jerusalem in 1067.
Yes, that's Turks as in Turkey as in the people who speak Turkish.