Hi, Celticpride –
I can only affirm what the other gentlemen have said here: that the arms only belong to descendants of the original armiger, and that while you may be one of those descendants, you will need to demonstrate it with documentary evidence.
It would be wonderful to know that you are such a descendant, although even then you may need to difference the arms (the nature of the difference would depend to a large extent on the nationality within Britain of the family).
So build that family tree and see where it gets you.
The fear of the Lord is a fountain of life.