how do i make a footstep sound randomizer?

First things first im making a showcase game and i want custom footstep sounds. So i have 2 audios i put up on roblox and i would like to use them. So how do i use math.random for audios?and i want to make it so when you walk the random sound plays.

You could add the sounds to a folder in ReplicatedStorage, then do the following:

local audio = math.random(1, #pathToFolderInReplicatedStorage:GetChildren())
audio:Play()

EDIT: Misread, didn't realize you wanted to replace a sound, lol.

You'll want to put this in a LocalScript in StarterCharacterScripts (since you'll be changing default attributes of every character)

player = script.Parent
sounds = player.Head:waitForChild("Running")

local audio = math.random(1, #pathToFolderInReplicatedStorage:GetChildren())
local id = "rbxassetid://"..audio.SoundId

sounds.SoundId = id