I have modify the file wordpress/wp-content/themes/mythemes/index.php, added some word. But when I reflush the main page, these word didn`t show up. I even delete the whole code of index.php & home.php. But the main page still show up. I am sure I modify under the correct theme folder. Anyone know what happen?
Wordpress theme structure is very flexible but there are some default page templates that must be inside your theme folder: WP Them files
index.php in the theme folder will be called only if the files above him in the hierarchy were not called:
You should follow the instructions in the link I think you should start with creating a page template, then create a page in wp-admin panel, on the side choose the page template you created before, and in that page template you can write your code/text, please note you should write the text in the wp-admin editor so you wont have to modify the template for every text modification:
here is some toturial of how to create a wordpress page template: page template wrodpress