Who knows php? I'm trying to build my first plugin from a php library that I found on github

I’m trying create a Recipe Parser plugin from a php that I found on github. Here: https://github.com/onetsp/RecipeParser but first I’m going to need to fetch content and then call RecipeParser::parse() by using $recipe = RecipeParser::parse($html, $url); print_r($recipe);. So, I found another github php that can help fetch rss content GitHub - arian/Rss-Parser: This is a simple PHP Rss Parser and I created an admin page but now I’m having trouble connecting it all. Like how do I build a form on the admin page that collects rss to be syndicated so it can fetch content and then call RecipeParser::parse(). Any help? I’ve thought of borrowing some functions from the cyberseo plugin but their php is too complicated for me.

This is the admin Page:

Plugin Name: Recipe Parser
Description: This plugin is used to parse recipe websites and produce structured data of ingredients, directions and other relevant information.
Author: Onetsp and Arian Github

//Admin Menu
add_action( 'admin_menu', 'recipe_parser_menu' );

function recipe_parser_menu(){

  $page_title = 'Recipe Parser';
  $menu_title = 'Recipe Parser';
  $capability = 'manage_options';
  $menu_slug  = 'Recipe Parser';
  $function   = 'recipe_parser_page';
  $icon_url   = 'dashicons-media-code';
  $position   = 4;

//Admin Page
  add_menu_page( $page_title,
                 $position );

if( !function_exists("recipe_parser_page") )
function recipe_parser_page(){
                <h1>Recipe Parser</h1>