How to make a block move up and down?

(New to scripting so ill prob be posting here a lot)

Ive tried some tutorials but they dont seem to work.

Script:

local model = game.Workspace.MovingFish3
Local platform = model.Fish
local start = model.Start
local finish = model.End
local bodyPosition = Fish.bodyPosition



-----------------------------------------------------------------------------
while true do
	bodyPosition.position = Start.position
	wait(4)
	bodyposition.position = End.position
	wait(5)	
end

One problem is that Position should be Capitalized Another is you aren't defining Fish you are defining platform.

local model = game.Workspace.MovingFish3
local platform = model.Fish
local start = model.Start
local finish = model.End
local bodyPosition = platform.bodyPosition -- Fish.bodyPosition -- Where are you defining Fish? Also is it bodyPosition or BodyPosition?

-----------------------------------------------------------------------------
while true do
    bodyPosition.Position = start.Position; -- Here
    wait(4);
    bodyposition.Position = finish.Position; -- And here .position should be .Position (You need to capitalize) 
    wait(5) ;
end;

That is the only problem I see with your code. If anyone else sees anything else feel free to comment and let me and the asker know. I hope this helped. If it did please accept this as the answer so that people know a solution has been found.