Need to take the strut off the car mate. Pretty sure that involves: removing brake caliper, driveshaft end nut, track rod end from strut, ball joint pinch bolt then use breaker bar to remove ball joint from the strut. Then undo the 3 top mount bolts (or now two) and drop strut off the car.
Depending on what springs you have, you'll probably need spring compressors. Remove the nut from the centre of the top mount, use spring compressors (if necessary) to compress the springs enough for youto fit the new top mount, replace the nut and tighten it up.