Linux Users: Kdenlive help needed

I'm using Kdenlive to make a video, and need help with this situation: I have a video clip in track "Video 1", and another video clip above that in track "Video 2". I'm not sure what the correct terminology is, but I want to set the "opacity" of the clip in upper track "Video 2" to about 50% so that the two video clips/tracks merge into each other. What I'm looking for is something similar to the "Dissolve" transition, except that I want the effect to stay consistent throughout the entire clip (not a transition between two clips on the same track, rather a merging of two clips with each other). If you can help, please reply with your bid and a bit of proof that you know what I'm talking about (e.g. a video clip of two clips combined using Kdenlive, etc...) Thanks!