Tumblr Post Opacity Options

[Kyra]

Hi, so I know just about nothing that has to do with any type of coding or anything else like that...But I'd like to request some help with a Tumblr theme (:

I'd like to know how to get my posts on Tumblr to have opacity like this: http://puu.sh/3rMYQ.png

See how you're able to view her background slightly through her posts? I want mine like that, and I can't find out how to anywhere...

This is the code of the theme that I'm using: http://freetexthost.com/i3zcm3d5vg
This is the code of the theme that she's using: http://freetexthost.com/hpn3qx4bo0

All help is appreciated. (:

[pandy]

I don't know what you can use on Tumblr or not, but this is how it usually is done.
http://www.w3schools.com/css/css_image_transparency.asp