The rubber portion of your blade will remove from the wiper arm. There are small 'claws' of metal on the secondary swivel portions of the main arm. If you look at how the blade itself is attached to the two swiveling sub-parts of the main blade assy, you will see the small 'claws' that the insert slips through and retain the rubber blade itself. Along the sides of the rubber insert, you will see the two chrome metal strips I referred to. At the end of the rubber blade, one of the 4 'claws' sit in indents in the rubber insert. The rest just sit in the groove along the length of the insert. This is what keeps the blade from just slipping back out of the 4 'claws' that form the 'channel' or path the blade sits in. After you locate the end of the rubber blade insert that has the indents in it and the 'pincher claws' inserted into them, you just grab, pull and wiggle the rubber part free of the claws. Once free, you can back out the rubber insert and free it from the 2 swivel units and main wiper arm. Once the insert is out, you will see two small strips of metal that sit in grooves along the length of the rubber insert.. in fact they will probably fall out of the groove if you don't take measures to keep them there. The metal strips provide rigidity to the floppy rubber part between the 'claw' support points on the swivels that attach to the main wiper arm portion (whew). The new narrow inserts have no metal strips to them so you will need to transplant the old support stips to the new inserts. There are little 'hooks' at the ends of the metal strips that must face the rubber side of the insert. Looking at the new insert, one side has the indents for the 'claw' to fit into and also an indent in the channel for the metal strip. Just put the 'hook' side of the metal strip in the groove, don't let it face out. Note that the 'claws' fit into a seperate groove on the wiper insert than the metal strips do. The metal strips fit in the upper groove, the ends of the claws fit into the groove closest to the wiper portion of the insert (the part that touches the windshield). That groove is wider also. Holding the two strips into the grooves provided on the insert, start spooling the whole works through the 4 'claws' 'till you reach the last one. Once there, force, wiggle, push the blade until the claw pops into the dents and keeps the whole works from slipping back out under use. This all sounds really long winded but if you look carefully at how the rubber blade portion fits into the wiper arm assembly, it should become apparent what parts I'm referring to and what I mean. If all this is still too confused, have a buddy or 'eager to please' autoparts counterperson help you out. Some inserts have the 'metal strips' incorporated into them as plastic. You won't need to swap them that way, just insert the new rubber blade part through the 'claws' and swivels until the end and pop it into the indents to keep it there. My fingers and brain hurts now, I need a nap... hope you figure it out.
P.S. I should be explained that the inserts are just the rubber portion of the wiper assemblies. You don't get the arm or any of the other parts you normally think of when you say 'wipers'. Also, the reason it's preferable to replace just them as they are cheaper and truly all that needs replacing unless something else is worn out or broken. Make sure you buy the NARROW inserts. The part number usually ends in an 'N', such as 21N. Get at least 21" long as that is the longest (on my Golf anyways) you will need. After installing, just cut the extra off on the shorter arms.
