How do I obtain ownership of real estate?

Your sister's estate will be dealt with according to Pennsylvania's laws of intestacy. If you are her only surviving relative, and her parents and descendants (if any) are deceased then the property should pass to you. At that time, you, as the record owner of the property can transfer the deed how you please.

You must file a Petition with the Register of Wills Office to be appointed as Adminstratrix of her Estate. Then you can administer the estate which will include the payment of Pa Inheritance taxes on the real estate and all other property. As the Administratrix you can deed the property to yourself as the sole beneficiary of the Estate.