verilog

since you are altera user.

modelsim is better than others.

coz, it is free.

if you want to start modelsim quickly.

here is a document I worte.

http://www.akiron.com/fpga/howtomodelsim.zip

if you want to try another one.

thre is iVerilog.

http://iverilog.icarus.com/

but, learning iverilog is also much work.