Android Development - Images and Logo copyright and license

I hope i am asking in the right place if not please let me know so i can move it to the correct place :)

I recently graduated from Android Developer Nanodgree(in Java), and i want to make an app and publish it on Google Play Store,

I want to be extra careful, so my question how to go about images or logos that i have designed by a designer or by my self ; do i have to register them somewhere? if so then where?

do i patent them ?

make a copyright?

i have no knowledge in this area , so how do you usually go about that? and if the designer supposed to do that? how can i verify it if i out-source a designer for that?