****I dont know how to script can anyone show me some basic scripting?
Not that this will really help you in any way since you don't know how to script but...
Use the UserInputService
to detect when the player presses Shift.
https://wiki.roblox.com/index.php?title=API:Class/UserInputService
From there fire a RemoteEvent or RemoteFunction to the server (unless you want to just set it on the client and let roblox physics update the server and all other clients):
https://wiki.roblox.com/index.php?title=Remote_Functions_%26_Events
From there change the Humanoid's Walkspeed to anything higher than 16.
I'm not sure if you want this is what you want but there are multiple plugins you can get for shift to sprint I'm not sure if you knew that or not. If you dont know about plugins then in studio go to Plugins>Manage Plugins and search for the shift to sprint you want, you may have to restart studio.