Clair, welcome to the forum!
Greg - I believe it was the 450D (see here
#5 is the pick, though the point of focus is more the shoulder than the eyes...
I'll refrain from further comments (those who know me will know why), but overall for a newbie, a solid start. Just be careful with where you pick for focus point to be, your highlights and start using the histogram to help you.
If you see that you are having a hard time focusing on the area that you want, I recommend that you lock your focus first. Meaning, you focus using the center focus point, click and half hold the shutter release to focus and lock it, then move your camera to the position you need to compose your image.
So basically, focus on the subject area, keep the shutter held, and then adjust your positioning. Just remember not to move forward or backward during this process as your distance to the subject will change.
The next thing I'll say is that you need to watch out for the direction of light. Look and see which direction the light is coming from and then position your model so that most parts of your subject will not be overexposed or underexposed.
Really, the biggest "negative" I see in these shot's is incorrect focusing.
As far as composition is concerned; well, it'll be a lot to type out, but continue to try different perspectives, angles, and poses. Familiarize yourself with some portrait compositions. Things like where what should be placed (i.e. shoulders, lower body, head etc...)
Overall, good job getting out there at a great location too, and taking some portraits. Keep practicing and please do keep us updated!