You need some specialized tools for this job, most notably a strut spring compressor and also a hydraulic floor jack. Without a proper spring compressor there is a serious danger
of injury so don't attempt this job without it. You can rent these at many tool rental or automotive supply stores.
The struts are held in place by a single nut on top, accessible from under the hood, and two bolts and nuts at the lower end. The top nuts may have covers over them, which you can just pry off with a screwdriver. Before removal you need to jack up and support the vehicle, remove the wheel, then support directly underneath the strut with the jack in a raised position (ie: don't use blocks on top of the jack to take up the space - you need to be able to lower it). Position the spring compressor over the spring coils and tighten it to compress the spring. This cages the spring so that when you remove the attachment nuts, it will not hurt you - make sure you do this FIRST before removing the attachment nuts. Then remove the upper and lower attachment bolts and nuts from the strut and use the supporting jack to gently lower the wheel hub from the strut, releasing the strut. You may have to persuade the bolts with a hammer. You should now be able to remove the strut with spring compressor still attached and then while on the floor, slowly release the spring compressor to separate the strut from the spring. Replace the strut with the new one and then compress the spring over it and place it in the vehicle in the reverse order of removal. Once reattached, you can remove the spring compressor, torque the attachment nuts, replace the wheel, and move to the other side to repeat the procedure. For torque specs and further information, check Kia Global's site