64 bit:
C:\Program Files (x86)\Steam\steamapps\common\Terraria
32 bit:
C:\Program Files\Steam\steamapps\common\Terraria
Just a quick correction here on all modern versions of Windows, Program Files holds 64 bit applications by default and Program Files x86 holds 32 bit applications.If you cannot locate the file, you can (on windows) locate it at
Code:64 bit: C:\Program Files (x86)\Steam\steamapps\common\Terraria 32 bit: C:\Program Files\Steam\steamapps\common\Terraria