Juniper plants need to go dormant for the winter which means putting it out in an unheated shed or garage (depending on where you live) for the winter. Also most homes have very dry air in the winter months from the central heating system which can pull the moisture out of new growth and weak branches very easily.

Your tree also looks like its in a deeper container so be careful how much you water. The soil cannot stay soggy.

Now you should get a pair of tweezers and start pulling the brown needles off. It can seem time consuming, but if you do a bit every day it'll look better in no time.
there are some good info resources on the internet like:
http://www.bonsaihunk.us
http://www.dallasbonsai.com/bonsai_tree_care_index.html

the best way to get help and ideas on your tree is by joining a bonsai club if one is located in your area. Here's a directory of clubs all over the US and the world.
http://freeplone2.openia.com/abs/club-listings/

our Japanese designed garden with pond,waterfall, bridges and bonsai junipers, shaped in ball form and hanging over the pond. now some start to get dying spots in the center or edges. I have cutout the dying part and tied the rest together somewhat, to fill up the vacated hole. My question, could there be disease? on the other hand the junipers are quiet old as is our garden, they don't need a lot of water, so how can they get fertilized? Dieter