Pathfinding to AI?

I have created a basic zombie off a tutorial but I need to redo movement into pathinding so that it does not like get stuck in front of objects so it can make it's way round the map to find the player and kill him for soul purpose of the game. However I don't know how to do this as it is very tricky. Please help!

Here is the current script:

torso = script.Parent.Torso
range = 50
armDmg=5
torDmg=10
target = nil

function findNearestTarget()
    plrs = game.Players:GetChildren()
    for i,plr in ipairs (plrs) do
        if plr.Character ~= nil then
            if plr.Character:findFirstChild("Humanoid") and plr.Character.Humanoid.Health>0 then
           tor = plr.Character.Torso
            if target ~= nil then
             if(torso.Position-tor.Position).magnitude < (torso.Position-target.Torso.Position).magnitude then
                print(plr.Name.." is in range")
                target = plr.Character
                break
            end
        elseif (torso.Position-tor.Position).magnitude <= range then
                print(plr.Name.." is in range")
                target = plr.Character
                break
                end
            end
        end
    end
end

function hitArm(hit)
    if hit.Parent ~= nil and hit ~=nil then
        if hit.Parent:findFirstChild("Humanoid") then
            hit.Parent.Humanoid:TakeDamage(armDmg)
        end
    end
end
function hitTorso (hit)
if hit.Parent ~= nil and hit ~=nil then
        if hit.Parent:findFirstChild("Humanoid") then
            hit.Parent.Humanoid:TakeDamage(torDmg)
        end
    end
end


script.Parent["Left Arm"].Touched:connect(hitArm)
script.Parent["Right Arm"].Touched:connect(hitArm)
script.Parent["Torso"].Touched:connect(hitTorso)    

while true do
    wait (.1)
    findNearestTarget()
    if target ~= nil then
        script.Parent.Zombie:MoveTo(target.Torso.Position,target.Torso)
    end
end