Hello! This tutorial is very simple, and will help you with a lot of games! Well, let's jump right into it shall we? First off you are going to need to figure out two parts that you want to weld together, and the variable names you want for each. For this example I'll be using "P1" and "P2".
P1 = game.Workspace.Part1
P2 = game.Workspace.Part2
Now that we have defined our parts we want to weld them together! Let's go onto the welding part! The welding part is fairly simple. All we have to do is create a new instance. If you don't know how to do that then this will help!
local Weld = Instance.new("WeldConstraint")
Weld.Parent = P1
Weld.Part0 = P1
Weld.Part1 = P2
Now in the code above you can put the parent to the weld with which ever one you find best fit. You could even parent it to workspace, but it's not recommended.
So inconclusion, this tutorial is fairly simple. If you want to learn more about welds I will make a tutorial on C1 and C2 with welds. If you have any questions feel free to send me a message!