I bought a Huffy from Wal-mart before I went to college. It was a 10 speed road bike. I used it as my primary means of transporation for a year and half. No car of my own, got rides back and forth from college, used the bike on campus and to go grocery shopping. Even after got a car, still used the bike to get across campus.
Still have the bike, it’s still in good shape. I don’t ride it, and need to replace the tires and innertubes (sat on porch for several years getting dry rot). But the bike is fine if all I want to do is pedal around the block a few times. I did replace the handle bars after an accident - got straight across bars instead of the curled road handles that came on it.
Your problem is not your bike. I agree you need to adjust the seat height so you can reach the ground while seated, or nearly so. Then you can get on and off without feeling like you’re going to topple over. Once you can comfortably get on and off the bike, it will be easier to begin riding. Just need to get motion going to find your balance.
I’m another that usually recommends a LBS but wouldn’t in this case. If you actually start riding much, you may want to reconsider that at some point in the future, though. There is a huge quality upgrade in those bikes.
You should be able to stand over the top bar with enough clearance that you don’t feel like you’d hurt yourself if you had to do it in a hurry. If that’s not true, you might want to trade it back for a smaller frame. 26" is the wheelsize, they’ll have different sized frames with the same sized wheels.
For now, drop the seat as far down as it will go, so that you can reach the ground easily when you’re seated. In the long run, that seat position will kill your knees, but for starting out, it’s much easier.
I like Princhester’s suggestions for getting started. Once you’ve gotten more confident of your balance then start moving the seat up. You’ll probably also want to adjust the seat forward/back to fit you.
HOWEVER, I will say that I’ve got one of those big-box-store cruisers and I can’t ride it because the configuration is so wrong that it’s painful. I’m not sure who thought that you could pedal with your feet behind the seat (and yes, the seat is all the way back).
Good luck and have fun!