Where to put html codes on wordpress php files -

I need help on editing or creating topics with the help of WordPress experts. I try to copy lol.garena.ph I am doing and what I have done so far was AN button, here are the codes:

    
 I do not know the problem I'm facing, where to put it on WordPress theme because I see that php files are. I insert the CSS part on style.css Have tried. It still does not work on content.php on the subject and the rest of the subject. I'm still new to Wordpress, please help me, thank you. 3.   
 
 
 I'm not really sure about your question, what are you trying to achieve But if you want to work on an existing theme based on your new theme, then I would suggest using WordPress Child Theme.  
  
 With Child Themes you can create a new kid style.css file for all your changes to CSS. The advantage of using a child theme is that you can make changes in existing CSS and PHP files without changing any core files.  
 It is very beneficial in the long run because it means that you have been able to update your WordPress topics without any existing CSS and PHP changes you already have.  
 I hope this helps in your quest to create your WordPress theme. I recommend watching WordPress tutorials at Treehouse (teamtreehouse.com) if you have an account or you can go to YouTube to find other great tutorials which can help.