Inside the folders that come with the DE2 board there should be a tutorials folder. Inside this is the design_files folder. Inside that is the pin assignment csv file you should have been provided.
Inside Quartus II (up top) Assignments -> Import Assignments... will bring up a dialog box where you can search for this file. Importing it will import all the pins. You can then name the pins in your bdf diagram the names of these pins and, as long as you have the correct device set up in your project file, everything should work.
