I use the split screen in vim very in-frequently, so I did not really know how to move from one screen to the other. There is also very little or no documentation that I found on this on the first page of google, so here it is :
press \”ctrl+w and ctrl + w\” to change to other window.
If you are not sure how to get the split screen, then you can type help split in vim to get the help on split screen.
Most simply said you can do so by \”ctrl+w s\”