Adding a Read More Button

I want to add that I made a “read more” button in photoshop. I just need to add the image and somehow have it linked to the corresponding post

Usually, that’s possible using it in the CSS – here’s one way:

https://codex.www.ads-software.com/Customizing_the_Read_More#Adding_An_Image

Read it but dont really understand it… Using more tags in post dont work for me. I add a more tag in my post but nothing shows up in the feed.

Just the default (…) that arent responsive anyway

what theme are you using?

Just the default (…) that arent responsive anyway

it seems that the theme is using the_excerpt() – review https://codex.www.ads-software.com/Function_Reference/the_excerpt on how to change that to the_content()
then re-read the resource linked by @wpyogi

This is the only thing I can seem to find in my functions.php that even seems relevant to more tags

}

// Limit Post Word Count
function new_excerpt_length($length) {
	return 50;
}
add_filter('excerpt_length', 'new_excerpt_length');

//Replace Excerpt Link
function new_excerpt_more($more) {
       global $post;
	return '...';
}
add_filter('excerpt_more', 'new_excerpt_more');

//Activate post-image functionality (WP 2.9+)
if ( function_exists( 'add_theme_support' ) )
add_theme_support( 'post-thumbnails' );

can something be changed here for readmore/more links to be shown on frontpage post excerpts?

you will need to edit the index template (index.php?) – see https://codex.www.ads-software.com/Function_Reference/the_excerpt

what theme are you using?