Altera has available a free online course covering the Basics of Programmable Logic.
This training will give you a basic introduction to programmable logic devices, focusing on FPGAs. By exploring the history of programmable logic technologies, you’ll learn about the architectural features that make up an FPGA device. You will see the advantages of using FPGAs for digital logic design. Finally, you’ll understand how design software, such as the Altera Quartus® II software v. 10.0, makes it easy to create and implement digital logic designs.
This course is just part of a whole lineup of free courses on CPLD and FPGA design from Altera.