title: How to modify opencart basic search module to a more advanced one?
body: <p>I am pretty new to opencart and I want to learn how can I create a more advanced search function. </p>
  
  <p>For example I have products in my store, some of them are blue and some of them are red. 
  How can I specify or where I can specify a product's color (but not in the title, something like an attribute)?</p>
  
  <p>And after that how can I search for red products? 
  I do not want to search by the keywords. I want a tab where to select the color and if I choose blue the search will show me all the blue products.</p>
  
  <p>I hope you understand what I wish.(and can you please give me some code examples: where to add what to add to achieve what)</p>
  
  <p>Thank you!</p>