Hi Nancy,
I have been shooting timelapses for quite some time already, and there are some issues you have to think of:
First, the speed at which you want to accelerate reality. Think of your shots as photograms of a video. A normal frame-rate is 20-30, that means that each second will show 20 pictures. If you take a picture every 5 minutes, each second of your lapse will equal 100 minutes in reality. Depending on what you want to shoot, you will need to use different shooting times and exposure times.
I would highly recommend you to use a tripod, so every picture has been taken with the same framing. If you plan for moving timelapses, then think of each frame before shooting, or maybe buy (or build yourself) a timelapse dolly.
Once you have taken the pictures, you can mount them with a lot of programs: for mac, I would suggest using the "Time Lapse assembler": easy to use and quick. In windows, the movie maker program itself is a good option (you will need to calculate how many seconds each frame will be, that is, if you are planning for 20frames per second, you have to put a duration of 0.05 seconds per frame).
I have a
post in my blog that explains those issues (mainly focused on northern lights, but the technique is interchangeable)
Good luck!