how do I find a player in workspace with player.Name?

The only foolproof way to find a player in the Workspace is to use GetPlayerFromCharacter() on the model that you assume is the player's Character. Furthermore, you'd be using FindFirstChild() before this to check if there is something in the Workspace with the player's name. Now, this is not a site where we give you code; we help you with existing code. As such, this is all I'm giving you.

If you are using a local script then you can just do:

local player = game.Player.LocalPlayer

local plr = game.Workspace:FindFirstChild(player.Name)

There's a property in the Player named Character which will give the model instance or nil. Sample of using Character

local Player = game.Players:FindFirstChild(name)

local char = Player.Character