New A57 Owner Questions

I'm the newest of the new to DSLR/T photography. I recently bought an A57 (with the 18-55mm f.3.5-5.6 kit lens) for my girlfriend (early Christmas present), and, as I suspected, I'm going to be the one who has to learn to use it. Since we live in China, the manual is in Chinese, and since it's already hard enough learning to take advantage of a DSLT camera's functions, I'm not going to learn all that vocabulary in Chinese at the same time. I'll probably eventually download the English manual and buy a book, but in the meantime I'm hoping the community here can help out with a couple questions.

I've got two questions offhand.

1 - How do I adjust the aperture in manual mode? Rolling the dial in front of the shutter button adjusts the shutter speed or, with the ISO button, the ISO, but I can't figure out how to adjust the aperture.

2 - Sometimes the camera refuses to take a shot. I feel like this has happened in many different modes, and it happens most often, but not exclusively, when the camera is at a strange angle or there's no apparent subject in the shot. Is this the result of a setting that may have been activated by default? I've missed some shots of active kids (we're both kindergarten teachers) because of this. I'd definitely prefer if the camera shot when I tell it to shoot, regardless of whether or not it's a good shot.

Thanks! I'll probably bother you guys again at some point, but this will help as a start.