The lack of detail makes it very difficult to help you.
A component list would be a good start, Motherboard (make/model) RAM (what type and how much),CPU (speaks for itself) and PSU (the wattage) to begin with and adding your operating system for good measure.
Now finding the above info will not be obvious but if you use SIW and scroll down to the home edition. Install it then run it and when it opens on the left hand side midway down will be a list of categories, clicking on each one will put up a fair bit of information on the right hand side. The top of this is where the info on make/model will be shown.