Help!!! download but not install on mac please read this

Help  my brother is the administrator on my computer and I don't know the password  I know how to use the app  without installing it but I don't see  the show content option when  I double-click the file it goes straight to install And as I said I don't know administrator password so I can't use the  program and I really want to.  I want to create my own custom content is there anyway I could possibly do it online?

 thanks for any help!