This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
If you do not specific a build file name, Ant expects a build file name build.xml to exist in the current directory. If you have a build.xml file, "cd" to that directory first and then run Ant. If you do not have a build.xml file, you need to create one.