i just want to know what to do to fix this problem so i can use photoshop
You answered your own question. For some reason your MacBook hard disk is formatted in MacOS X Extended Case-sensitive. I have no idea why; the default formatting in MacOS X is not case-sensitive. Photoshop does not support case-sensitive hard disks, so you would have to reformat your hard disk to get it to install. Remember that reformatting destroys all data, so make a backup first!