FPGA Prototyping By Verilog Examples: Xilinx Spartan-3 Version

Not an online course, but my go-to recommendation is "FPGA Prototyping by Verilog Examples" [1]. Or, if you want to learn VHDL, [2].

[1]: https://www.amazon.com/dp/0470185325

[2]: https://www.amazon.com/dp/0470185317