You have downloaded the sourcecode of JFractionLab! This is a description how you can compile the program on a unixlike system. On windows you can read mkJflJar.sh and run the analogous commands. 1. Install a JDK! 2. Unzip the source! 3. Go to your homedirectory 4. Copy the script mkJFLPack.sh to your homedirectory and run it like: ./mkJFLPack.sh ./mkJFLPack.sh 083 foo/jflsrc_083