First of all - welcome to BC ! Second - relax, you have come to the right place for help !
First of all, can you download and run 'Speccy' and 'MiniToolBox', both of which are free downloads from BC. This is the link to 'Speccy' -
and these two images show you how to get the URL which is all you need to paste, the URL is anonymised -
This is the link for MiniToolBox -
Select the boxes shown in the image below when you run MTB, It will then produce a report in text format. Open the file and copy / paste all the test into your next post -
What makes you think you need to re-install your operating system? If your hard drive is getting full then the answer is to, first, clean out any temporary files, and then to move any data - work, photos, music, videos - that you don't immediately need to an external drive of some sort. Once you have moved them to the external storage you can safely delete them off your C:\ drive. One other small point - if your 'Recycle bin' is full, try emptying it. files are not actually deleted off the hard drive until you do this.
But post back with the information above.