When you post images, make sure you grab the URL with JPG at the end.
On Postimg, http://postimg.org/image/vz93f2ecp/
Click on the "show codes" link at the bottom.
Then copy the "Direct Link".
Here on Polycount, click the yellow "Insert Image" button, and paste your URL.
Replies
If you want an actual bump you need to use a normal map.
The roughness map is for reflections.
On Postimg, http://postimg.org/image/vz93f2ecp/
Click on the "show codes" link at the bottom.
Then copy the "Direct Link".
Here on Polycount, click the yellow "Insert Image" button, and paste your URL.