Transmission will not shift out of 1st but...

If it is a manual it could be the shifter forks or compression plate. If it is an automatic, it may be the clutch material in it is degrading too fast and you have nothing left to shift it. I would recommend you take it in to a tranny shop. If you want a challenge you can always rebuild it yourself but I would not do that unless you are willing to spend some time doing it and willing to take pictures of where the parts go.