how to connect outdoor led rgb to existing 12v cable Answered

Hi all

In my backyard, I already installed a 300 watt transformer.  I connected/ran a 12v low voltage cable around my back yard.
It was for an uplight project.  Now, I removed all those lights (the 12v cable still there) and want to install LED RGP lighting.
Im stuck at how to connect the RGB controller to the existing  12v cable.

Any advice is greatly appreciated. 

Thanks a bunch,
Kevin