Im trying to install the newset java update so i can download the free version of minecraft?

Every time i go to down load the newest java update it works fine when it askes me to run it, i say yes, then it party downmloads it, askes if i want to comtine then i say yes, an dit jus closes out, and notinh works.. whats going on!!! i really wan tot play mine craft and i just cant ge tit to work!