It looks like you've made a custom tilemap there judging by the picture. If you want it to glow you will have to copy the image on your tilemap 3-5 times and change the brightness/contrast/etc. on each one in sequence then change your tilemap code from:
<frame>0 0 0 0</frame>
to
<frame time="200">0 0 0 0</frame>
copy that 3-5 times then change the coordinates based on however you set up your image. Here is some example code:
<tileset level="-300">
<sprite scale="16">
<texture>tilemaps/waterset2.png</texture>
<frame time="200">0 0 64 64</frame>
<frame time="200">64 0 64 64</frame>
<frame time="200">0 64 64 64</frame>
<frame time="200">64 64 64 64</frame>
</sprite>
</tileset>