OnClick Function problems

my fisrt time here... I want to ask what I'm doing wrong? I've tried a lot of things to do this and I have a lot of different errors like "else without if", my setBackground is not working, but... I made everything I found here or on Youtube or Internet a lot, I start to learning to program Android Studio from nails and I've make some good things like change activity Onclick, I make hide/show text function on this same button, the Switch variable from to change activity, And soooo... I want to make a simple thing: Click - I have one image, I click again I have the first image... That's all

Thanks in advance people <3