Get the wheels off, struts out and line up the top-mounts with the holes making sure everything is going to fit nice & tight.
Take them off and take the two silver metal parts out of the middle of the mounts
The two metal parts that fit inside the topmount, where they meet in the middle;
The bottom one (not threaded) obviously goes onto the strut first (straight on top of the spring cap)
On goes the bottom half of the topmount, them the other half of the metal insert, which should of course catch the threads of the strut. Tighten up.
Maneuver the strut into the wheel arch (the hardest part of the job) and line up the two halves of the topmount so your 3 bolts meet the bottom half.
Screw together with an allen key and make sure nothing is fouling your strut & brake line before you bolt the strut to the hub again.
Repeat for the other side and you're done. Don't forget to put your wheels back on
*** What suspension have you got?
If it's standard setup you'll need spring clamps so you don't end up with it being a part of YOU instead of the car lol