How do i add ice block if the player is frozen?

Yes, this is technically a request, since you didn't attempt to create the ice yourself, but since you did try to make the first part of the script, I'd like to consider it "Help" more than "request", since it's also a simple thing.

What you need to do is create a new part, and then put it over the player, like so:

function onTouched(part)
local hu = part.Parent:findFirstChild("Humanoid")
local he = part.Parent:findFirstChild("Head")
local la = part.Parent:findFirstChild("Left Arm")
local ll = part.Parent:findFirstChild("Left Leg")
local ra = part.Parent:findFirstChild("Right Arm")
local rl = part.Parent:findFirstChild("Right Leg")
local to = part.Parent:findFirstChild("Torso")
local ice = Instance.new("Part", workspace)


if hu~=nil then
he.BrickColor = BrickColor.new(1013)
he.Transparency = 0.7
he.Anchored = true
la.BrickColor = BrickColor.new(1013)
la.Transparency = 0.7
la.Anchored = true
ll.BrickColor = BrickColor.new(1013)
ll.Transparency = 0.7
ll.Anchored = true
ra.BrickColor = BrickColor.new(1013)
ra.Transparency = 0.7
ra.Anchored = true
rl.BrickColor = BrickColor.new(1013)
rl.Transparency = 0.7
rl.Anchored = true
to.BrickColor = BrickColor.new(1013)
to.Transparency = 0.7
to.Anchored = true

ice.Size = Vector3.new(4, 6, 4)  -- Since you called for 'ice', it makes a new instance of a part.
ice.CFrame = CFrame.new(to.Position) -- Position the ice at their torso
ice.Anchored = true
ice.BrickColor = BrickColor.new("Cyan")

ice.Transparency = 0.5

end

end

script.Parent.Touched:connect(onTouched)

Though requests aren't something we should take here, genuine requests for 'How do I do this?' should still be answered if they're simple enough. Have a lovely day.