I've done exactly this on my Subareno Cliopreza. It's quite involved to put the front pick ups in. As said above, you need a hole for the tubes to go through to the top mounts.
Tack the horizontal bars in place first, without the main front roll cage bar in place.
Tack in the diagonal bars to get the position right.
Fit the front cage in place temporarily to make sure everything lines up. Grind off the tacks, and remove the horizontal and diagonal bar still tacked together. Fully weld the joint between the two bars. (You can't do this with the bars in situ).
Refit the welded front pick up bars complete, and fully weld to the top mount.
Now you can weld in the main roll cage, remembering this needs to be dropped down so you can weld around the top of the bars. Once the main cage has been welded together, shove it forward to line up with the front bars already fitted, and weld in the main cage.
Only photo I can find to help you, thought I had more!
Here you can see the front bars are welded in, but the main front hoop has not been welded to it yet.
There's some photos on my facebook page which may help,
https://www.facebook.com/Gould.Clio?ref=hl