To the point: just put it in the classpath.
- , /path/to/package/root / JAR, /path/to/file.jar. . Unix, OS X, - : ( Windows ;).
, , .
plain javac , -cp, . , IDE, " " ( , ).
java .class, -cp . java -jar ( - UI- ), executabele .jar, Class-Path JAR MANIFEST.MF, JAR.