origin of logarithms (napier)

Hi folks. I am trying to unravel the mystery of the creation of logarithms. i ave already read an article about this subject but alas I have not yet quite understood it, i didnt follow the meaning behind the creation of three tables etc. anyway, I have gleaned the 'connections' between A.P and G.P. with reference to indices in a G.P. series. I would really love to know how to CREATE a table of logarithms based upon modern ideology, ie use of A.P.s and G.P.s. Could anyone help, please?

t.i.a.
gaz