Answer:
in order to make a weld you need a welder
The above post is a little simplistic but you basically weld using gas or electricity to melt the base metal allowing you to add metal via a flux coated or bare rod. If using gas to melt you would use a bare rod to add - if using electricity to melt you would add a bare rod (with a covering gas) or flux coated rod (which forms its own gas). There are so many welding processes that techniques and equipment vary widely.