Using "background-image" in footer template. (I did not know how to describe my problem)

[Greenpk]

Recently I added a back to top button on my website. (It is not my code, it is someone else who made this.)

Anyways I just want to know something about the css styling of it, by using images to describe what is going on.
[ATTACH=CONFIG]n4029694[/ATTACH]

This is my button, removed the background color and tried to use background-image instead.
I uploaded the image file to this directory: images/primus/sandy/buttons
I tried to switch out the "background: #FFF;" with "background-image:url('forum/images/primus/sandy/buttons/top_button.png');"

I am currently using html <style> tags with css, so I have no idea how to make the image appear inside the back to top button.

Image is like 144px wide or something. I have tried to adjust the padding, but that doesn't work either.

[Greenpk]

<script type='text/javascript'>$(function(){$(window).scroll(function(){if($(this).scrollTop()!=0){$('#bttop' ).fadeIn();}else{$('#bttop').fadeOut();}});$('#bttop').click(function(){$('body,html').ani mate({scrollTop:0},800);});});
</script>
<style>
#bttop {
border:2px solid #4adcff;
border-radius: 15px;
background: url('images/primus/buttons/top_button.png');
text align:center;
padding:0px;
position:fixed;
bottom:35px;
right:-15px;
cursor:pointer;
display:none;
color:#fff;
font-size:15px;
font-weight:900;
}
</style>

that is the script being used to create the button.