I've been looking at microscopes a lot lately. And this is what I've found:
Connective Tissue. Each little black dot you see is a little "brain" for an individual cell, called a nucleus. The red stuff is just all the other junk in a cell. This slide is a tendon, which means that it's used to anchor a muscle to where it's supposed to be, so it's not flapping around uncontrollably.
Bone Tissue. Cross Section. Those big dark black circles you see is where blood flows in to supply nutrients. The smaller black dots are cells that build "bone" as you probably think of it, that hard white stuff.