This is going to sound incredibly harsh, but you're not working with him nearly enough. I'm not sure where you're from, but it gets dark at about 8 30- 9pm here in the middle of summer. If he's turned out in a paddock all day, he probably doesn't much look or act like a show calf should at this time in the year.
It sounds like you only have a few weeks left until your show, so there is a limited number of things you can do.
1. Get him in and feed him in a feed pan before you go to school. Tie him with his head up and blow/comb him out, and then either put him in a pen inside with a fan, or into a shaded area outside.
2. Work with him as much as you possibly can with other people around. Get a friend or two from your 4h or FFA club to come out and just get him used to other people being around.
3. Put a radio on for him to hear at all times. This will help get him used to different voices and sounds.
4. Whatever you do, do not show him if you think he could be a danger to anyone. A big, scared steer can hurt a lot of people, and a calf project is not worth ANYBODY being hurt over.
Now, some of the hardest advice I have to give you. If you really want to do well and show cattle, panicking and scrambling for solutions three weeks from your target show date isn't the way to do it. I know there are other priorities and obligations in life, but showing a calf is a serious business because of the financial and time investment put into it. If you feel you can't be with your calf at least 3-4 hours every day, at least 100 days prior to your show, maybe you can look into other, less intensive livestock projects.
We struggle with this as a family, because it is what I do for a living, but we also have to work a Jr project in there for my 13 year old brother. We make lots of compromises, like I'll get the cattle in and washed/fed every morning if he rinses and walks exercises the heifers in the evening.
