I tried and apply the theme you said and seems having problems, the icons doesn't work.
from toad007's post. I like his theme
should I install mate 1.22 version first?
The icon pack is separate from the gtk theme. Tomorrow I will post a link to the icon theme pack and install instructions. You don't need to upgrade...
I'm having issues about installing Sierra-light.. and my panel is not transparent 
The icons are not part of the Sierra light gtk theme. The icon packs are separate. Also, the theme will not make the top bar transparent. You can right click on the panel, select properties and choose the transparency that you want, but in order to get the Ubuntu MATE notification panel transparent requires a little work. I can link to a thread tomorrow that details that.
So, are you having problems installing the Sierra light gtk theme, or the icon pack?
In order to make the panel transparent visit this thread...
For the icons you need to download this icon pack....
once you have downloaded the icon pack extract it and place it in ~/.icons
Then go to the appearances settings in MATE and select customize, click on icons, then select the icon pack.
transparent is not working.. I already tried your help but nothing happpens.