How to install operating system?

How to reformat PC?

First its not a good idea to piggyback your question on someone else's. This can lead to confusion. You should start a new thread. So I've moved your question to its own thread. I've also merged the questions.

To install an operating system you need to insert the disk with the install routines on it then follow the instructions.

To reformat a drive, you need to boot to drive other than the one you want to format that has the format utility on it. Then run that format utility.

If you can explain what you are trying to accomplish we may be able to help more.