html - Broken image with bootstrap default navbar -

i have relative link image on computer on i'm developing ruby on rails app. i'm using bootstrap customize style , have used code source image top left brand placement. here's bootstrap link i'm referring to: http://getbootstrap.com/components/#nav

i'm trying add custom brand image, keep getting broken image error (404 file not found) when open localhost:3000 test in browser. not sure if image size issue or novice file location error. have tried several types of images (jpg, jpeg, png, etc.) , different image sizes, keep getting same error. basic html/css error, , i'm struggling figure out how fix it. appreciated!

below partial _header.html.erb file in reference bootstrap navbar:

<nav class="navbar navbar-default">  <div class="container-fluid">   <div class="navbar-header">    <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1">      <span class="sr-only">toggle navigation</span>      <span class="icon-bar"></span>      <span class="icon-bar"></span>      <span class="icon-bar"></span>    </button>    <a class="navbar-brand" href="#">      <img alt="humanify" src="../../app/assets/images/logo_final_march2015.jpg">    </a>  </div> </div> .... 

you should using image_tag.

try similar this:

<nav class="navbar navbar-default">  <div class="container-fluid">   <div class="navbar-header">    <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1">      <span class="sr-only">toggle navigation</span>      <span class="icon-bar"></span>      <span class="icon-bar"></span>      <span class="icon-bar"></span>    </button>    <a class="navbar-brand" href="#">      <%= image_tag "logo_final_march2015.jpg" %>    </a>  </div> </div>