Can I code with my phone? Help

Hi, I don have a computer nor ipad or table, just an Android phone,  I was watching some videos about how to code, at least just trying to change the background, but I don't know if is the way that I'm codding or what, I was following the tutorial but won't show

For example, the code that I'm using is the following (don't judge plz):

<style>

. profile}

background: url(https://i.gifer.com/vm.gif);

{

</style>

Also, I tried doing that on the app and shows but everytime that I save, it's like blank, like show the code but it's not showing that in the profile, here it's the Attachment