CAN ANYONE HELP ME WITH THAT?

there's alot of people here that can help. Post your relevant code so we can see and relate to what you are asking help on.

Add font-awesome or one of the other icon stacks.
<link href="//maxcdn.bootstrapcdn.com/font-awesome/4.2.0/css/font-awesome.min.css" rel="stylesheet">

Example from Font-Awesome ( Font-Awesome ):

<div class="list-group">
  <a class="list-group-item" href="#"><i class="fa fa-home fa-fw"></i>&nbsp; Home</a>
  <a class="list-group-item" href="#"><i class="fa fa-book fa-fw"></i>&nbsp; Library</a>
  <a class="list-group-item" href="#"><i class="fa fa-pencil fa-fw"></i>&nbsp; Applications</a>
  <a class="list-group-item" href="#"><i class="fa fa-cog fa-fw"></i>&nbsp; Settings</a>
</div>

You just want to add something like this to your css.
i:before {content: "▼";}
This will add a "▼" befor all the options. If you want to only have it on some of the links, you can create a diffrent class for it and only add it to the ones you want.