Unfortunately we are now in the thick of breeding season, so time is in rather short supply for a length answer.
I think you are on the right track, though, if you believe you don't have enough light. Flash photography is a must for the kind of shots you are likely striving for. I use two flashes mounted on a bracket my camera sets on. Often I use a work bench where I have a third flash mounted directly overhead that is triggered when the other flashes go off. Seems like a lot of light, doesn't it?
But there is a reason for that: depth of field. One of the idiosyncracies of photography is that the control of depth of field, especially for close-up work, is critical, but not exactly intuitive for a beginner. The problem is that depth of field is controlled by the size of the aperture. The smaller the aperture, the wider the depth of field, but at the expense of the amount of light that is entering through the lens. Seems simple enough, but this changes everything else at the same time. The smaller aperture also allows less light for the exposure, so somehow you need to accomodate for that. One way is to increase exposure time, but photographing live animals pretty much guarantees that you want faster exposures, not slower ones, to freeze the action. The other option you have is to increase the amount of light available.
In 35mm photography and such, there were four variables you could play with for controlling depth of field that were interrelated: lens aperture, amount of light, length of exposure, and film exposure speed. With the new digital cameras, you can still adjust the supposed exposure time of the digital "film", but I have no idea what this really does to the exposure. Perhaps it is just a simulation of the effects of changing film in a 35mm camera. All of the other variables should be the same in your digital camera and be fully controllable.
Anyway, I went on about this longer than I had intended, but I gave you some keywords to explore in more depth. I will say this, though, there is NO substitute for experience. Just experiment as long as it takes for you to get to know your equipment. With a digital camera, you can get instant feedback. When I was learning this stuff, I didn't learn my mistakes for maybe a week or more when I finally got the film back from being developed. The instant feedback will make the learning curve a whole lot easier to handle.
Oh yeah, here's another keyword to investigate: TTL (Through The Lens metering). You will HATE flash photography without it!
And here is a quick hint to get started on the right road: Set your camera to aperture priority and set it to the smallest aperture available. The trick here is that the LARGER the number (f-stop) the smaller the aperture. Remember what I said about being non-intuitive! Then do whatever is necessary to get a good photo by changing everything else EXCEPT the aperture. If you CANNOT do this with your camera, then you may have to accept the fact that your camera just may not be up to the task to give you the results you want. Some of the digital cameras MAY have a fixed aperture.
Anyway, good luck!
