It depends where you want to advertise..
On the internet, Hi-Res means 72dpi.
Why? Because computer monitors can only see 72 dots per inch.
For flyers and print work, I recommend a minimum of 240dpi. At least 300dpi.
Your camera will most likely shoot around 72-200ish dpi, but if you open it in a photo editing software, you could crop it with 300dpi and wala!
Hi res just means higher resolution which is better quality when printing.
Higher number dots per inch (dpi) mean bigger image and better quality. But remember, for internet purposes, you only need 72dpi.
Look in your camera menu's, and make sure you are shooting with maximum megapixels and maximum quality (image quality).
Best,
-AC