what you need to do maxii is to reinstall the operating system (some version of windows, i assume). the system formatting and partitioning will be done as part of the install itself so you can start using the pc as before.
but i am afraid it may be a bit confusing/frsutrating for you to do it all by yourself, but if you are ready, i could try to provide the necessary instructions so you can go though the process
you may begin by looking for the installation media. mostly, it must be a cd/dvd that you got along with the computer. once you have it, everything else is easy.
then there must be a drivers cd/dvd. these two essentially make up the operating system. other application software if you have any, can be installed after these are installed
i assume you may not have as much access to this website since your pc is dead, here is some instructions on the installation itself.
when you find that cd, just power on your pc, open the cd drive, insert the media and power off and on again. windows will take over from there. it will be slow, so you may get a newspaper/magazine just to kill time
most the questions during the installation are easy to answer, such as region, time.etc. but to the question about formatting, say yes even to the warning: data loss alert (since yours is a brand new drive, there wont be any data) and to the question about allocation, just answer the whole drive as C. this should help you when you are not sure about what to answer
then there is the drivers, just put that in the cd drive and select install all drivers. it will reboot a few times, but your pc will be ready once it is done