Lightroom 6

I had to load my Lightroom on a new computer and I am having an issue that seems like it should be such an easy thing.  I selected my photo and when I go to develop the picture is not taking up the whole grey area so I can edit it.  It is in the "navigator" section in the left corner.  Any editing I'm doing is showing in the little small square of the picture.  I cannot figure out for the life of me how to "blow up" my picture so I can edit it on the main screen right in front of me.  I don't know what I'm doing wrong?!  Please help as I've already had many tears.  I don't know how I'll edit pics, right now this is useless for me because I can't even use it to edit.