Nice job for a 1st timer and it looks like you got a nice welder there.
Im not telling you how to do suck eggs but would you weld that onto your garage door or bolt it on? If your bolting you will struggle to get a nut or bolt through them holes as they are a bit close to your handle the bolt head/nut has no room to turn maybee weld them up and drill further out a bit might help.
not bad first time project if you do anything like similar in the future you may consider grinding the joint into a v shape that way you wont remove most of your weld when clean it up also you will have welded more area together then you would by simply welding the joint as it was cut.