I recommend to use Smack with a build system that is able to include Maven dependencies, which will automatically resolve all dependencies of Smack. Do not use the Smack jar files directly.
+1 to what Flow says. The world has moved on from downloading JAR files and manually sticking them in your path, the time invested in understanding a modern build tool will pay dividends. My preferred tool right now is Gradle. For your purposes you probably only need a few lines of config to get going.