Open your emulator's Lua Console (usually under Tools > Lua Console ).
C1_EBDetect3-NiceL.lua appears to be a specialized Lua script often associated with or TAS (Tool-Assisted Speedrun) tools, specifically for the game EarthBound (Mother 2). Its primary purpose is to provide real-time data visualization and "Encounter Bug" detection. Core Functionality C1_EBDetect3-NiceL.lua
Browse to and select the .lua file. The overlay should appear immediately over the game window. Open your emulator's Lua Console (usually under Tools