I want to insert some code into the user profile page(domain-name.com/user/username), while searching in this forum, I found a post that was pointing at the file:

ow_system_plugins/base/views/components/user_view_widget_table.html

The code in this file is very similar(equal IDs etc.) to that what I see when I look at the source code in the browser, but changing the file has no effect. 

Is this the correct file?

Is just c&p the code into the file on the server enough? Or is this a template engine of some kind that needs a compilation step?

Here is the point where I want to add something:

Thats the code:

....

<div class="user_profile_data" style="position:relative">

 {if $ownerMode || ($adminMode && !$superAdminProfile) }

     <div style="display: none;" id="edit-profile" class="ow_edit_profile_link">

            <a class="ow_lbutton" href="{$profileEditUrl}">{text key='base+edit_profile_link'}</a>

     </div>

 {/if}

<h1>I really want to see this Heading</h1>

<table class="ow_table_3 ow_nomargin">

....