To put the two parts together, grip each piece close to the assembly point - as close as you can - and slowly wiggle them together, pushing gently. Only allow your hands to touch the smooth cylindrical sections of the flute and do not clasp any of the moving parts. Rods and keys are easily bent and expensive to straighten. Bent keys cause leaks resulting in poor tone quality. The pieces should slide together easily. If you are having trouble or are having to use force to get them together, try cleaning the joint with a little alcohol. If you are sill having trouble, then you should probably take your instrument to a repair shop and have it examined.