Help writing a 'script' to open a java application in dash home

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http://ubuntuforums.org – Hello, I apologize in advance if I am posting on the wrong forum, or if what I am trying to accomplish is impractical. I have Ubuntu 12.04 LTS. I found a nice little program which takes a .pdf file and opens it, and crops the .pdf to size. This is called briss-0.9. I can run the application by executing following command in terminal: java -jar briss-0.9.jar or java -jar briss-0.9.jar cropthis.pdf. For the moment I have this file in my downloads folder. But every time I want to crop a .pdf, i have to cd to the DL folder and execute the command. What I would like to do is to simplify this i (Hardware)