Hi gagirl1! I started out at 355 pounds when began to exercise. I joined Curves gym which allowed me to modify my work outs and get my body used to exercise. It closed and I recently switched to a regular type gym. In your case if you're in a rural area an elliptical might be ideal for you. I was asking my trainer (who actually has a degree in fitness and owns the gym I go to) told me that the elliptical is better for me because it's low impact on the knees and it works the upper body too compared to a treadmill which is pounding when you're walking and you're not doing anything with you're upper body. It was hard for me at first on it but after a while it's now my favorite thing and I am up to 25 minutes on it in addition to everything else I do.
I use it with the treadmill and I also lift weights. It's really important to make sure and build your lean muscle while you're building up your endurance through cardio. There are lots of video's on youtube on ways to lift weights at home without using gym equipment. Can goods work wonders!