If you use these install instructions, please cite: Graham G.M. Alvare, Natalie K. Björklund, John Schellenberg, Richard Sparling, Brian Fristensky; Koala: Overlaying Local Gene Expression Data on BioCyc Pathway Diagrams
Install Pathway Tools
Download pathway tools
Locate and run the installer (this will likely be on your desktop)
Go through the install instructions (if you don't know what to do, just keep clicking Next, and you should be fine)
