Hi DixieNurse:
You asked:
Where is Jesus' kingdom, and what exactly does that mean to the Christian??
I can't speak for Christians but I can comment upon what I understand of the scriptures.
YaHshua (Jesus) as a man upon this earth spoke largely about the Good News of the kingdom of YHWH ('God'). It was also referred to as the kingdom of Heaven in the scriptures. That means to me that the kingdom both belongs to YHWH and its 'location' at that time was heaven. I believe its location is still heaven and it is still the kingdom of YHWH according to my understanding of the scriptures.
Further I believe that upon the return of the Messiah to this earth He will become the ruler of the government of the kingdom of YHWH and will govern all the nations of the earth for 1000 years in the righteousness of YHWH accompanied by the saints of this age who will have become the government under YaHshua (Jesus) for that age as spirit beings.
It will be a contrasting age compared to this one in that this age is being ruled by satan with the emphasis upon evil. The 1000 year age will
be the opposite as it will be rule in the righteousness of YHWH. The kingdom of YHWH at that point will still have as its location, heaven.
In the age following, the 1000 year age, all who have ever lived will be resurrected, be given the Holy Spirit whether they want it or not and be shown the history of the two previous ages. At that time it will be very obvious which is the better way of life; a life of choice from among good and evil, or a life of just being able to choose only good. The decision will be a no-brainer as the books of the scriptures will be open to all who never understood them or had access to them in this age and they will choose good and life. They will judge in that age, or 'day', to live the same way YHWH lives.
At that point in time all will have repented and demonstrated they believe YHWH by willingly and willfully following those things that were written in the books of the scriptures. That will give cause to usher in the next age - the age of the coming of YHWH and his kingdom with the New Jerusalem to this earth. That will have been made possible by the work of YaHshua and the government of the kingdom with His saint as they will have wiped up and disposed of all sin from the earth so the earth could become the home of righteousness and the throne of YHWH beginning from Jersusalem.
That is the day we are admonished to hope for and seek out by first concerning ourselves with the kingdom of YHWH and its scepter of righteousness so that we can be prepared for the coming of Him and His kingdom when it comes to earth.