Line up the two parts so that the colour you want in the centre is the inner part. Insert the larger blade of the outer part into the slid below the smaller blade of the other. Turn the heart to the other side and do the same here. When you weave the central part the strip is much wider than the slid you have to put it into. Make a soft bend and straighten afterwards. A pair of tweezers is a handy tool.
Please find a picture guide, illustrating the sequence of weaving.
PaperMatrix 
Can’t assemble #018 Heart.. Please help!!!!
I have included a picture guide on how to weave. I hope this will help. The principle is to weave the squares closest to the heart blades first – in both sides. That is you have to weave first a red strip, then a pink etc. Lene