Hi all! I am new to the group because yesterday I went and bought a juniper bonsai from a florist but after getting it home I noticed some of the needles were yellowing and some of them were a really dark brown. After reading about how late junipers show they are dying, I am worried I have bought a gorgeous tree that is already on its way out. Can any of you guys help? Pictures of said spots are attached. I have been keeping the little guy outside since I got him.

It's to late, put it out in the sunshine. This type of plant, won't last long inside. If they survive, the first, long hot summer, they should be okay.
I would leave it in that pot till spring. Here's the fun part, don't underwater, or over water.

A good place to start www.bonsaiempire.com/tree-species/juniper

tree looks fine to me. seems those branches have died off. can be stress from relocating it or its simply not receiving enough light cause other foliage is covering it.