Changing output format of Website url field
From JReviews Documentation
If you want to change the output format, click on [Click here for Advanced Options] and advanced field options will slide down.
This is the default output format of the Website url field:
<a href="{FIELDTEXT}" target="_blank">{FIELDTEXT}</a>
If you want a custom anchor text, replace the second {FIELDTEXT} with your text:
<a href="{FIELDTEXT}" target="_blank">Visit Website</a>
That is useful if the url's will be very long, so a custom anchor text will prevent the url from breaking the layout.
You can also use the value of some other custom field as the anchor text, replace the second {FIELDTEXT} with the name of that other custom field, like this:
<a href="{FIELDTEXT}" target="_blank">{JR_SOMEFIELD}</a>
Or you can use an image as link anchor:
<a href="{FIELDTEXT}" target="_blank"><img src="images/mylink.gif"></a>
The image should go into the Joomla's "images" folder in the root.