My garage is wired with a 220 outlet but the plug is for a dryer so I got the outlet I needed the new outlet has 3 conections the old one has 4 I know the red and black are hot but not sure what to do with the white and ground should they be connected to gether or do I not use the white well thanks for the help

Thanks brad"

White is the neutral. If your welder is 220 volt only you do not need a neutral but you MUST have a ground.

A electric dryer has a 115 volt motor and that is the reason a dryer has to have two hot legs and one neutral. There was a code change a while back and now range circuits/dryer and others have to have 4 wire hookups.