1) Install Java. Instruction:
https://ubuntu.com/tutorials/install-jre#2-installing-openjdk-jre
2) Create a folder for the server and download the paper to a folder
3) Create on your computer a .txt file with content
java -Xmx1024M -Xms1024M -jar name.jar nogui and transfer the file to your Ubuntu computer in server floder
4) Open terminal and enter these commands: