How do I use TweenService with the code I made?

Hello, I made this code... but there is one problem is that it looks like it is teleporting from stud to stud, and I am trying to make it's movement smoother. But however, I don't know how to do that, Here is the code I made.

while true do
 wait(3)
wait()
 for i = 1,90 do
 script.Parent.CFrame = CFrame.new(script.Parent.Position + Vector3.new(.5,0,0))
 wait()
 end
wait(3)
 for i = 1,90 do
 script.Parent.CFrame = CFrame.new(script.Parent.Position - Vector3.new(.5,0,0))
 wait()
 end
end

Also, the purpose of the script is to make the part move from location to location. If anyone can solve this problem, it would be appreciated.