Lay out the pattern in rows until you are happy with the design. (I usually leave it out for a few hours and go back to look at it periodically.)
Sew the blocks together into individual rows. I generally trim the blocks to be the same size or in case of slight differences, I split the difference between the smaller block and the larger block.
Once all the rows are sewn, I press the rows. I generally press the seams to ONE side on all the odd-numbered rows and to the OTHER side on the even-numbered rows.
That way, once you flip two rows to sew them together, the seams will nest. I pin the pieces and sew the rows together. Repeat until done and gently press the top.
Measure across the center of your top in one directions and cut/sew the border fabric to that measurement. Sew on the border on two sides. Now measure across the center of the top with the sides on. That is the measurement for the next border length.
As far as color goes: If you want to use black, I suggest using a narrow border of a contrasting color as the first border. Otherwise, black on black, the border won't show.