This guide is pretty good. it's an overview: http://www.davesite.com/webstation/html/
meta tags are just hidden information about the page, such as the description and keywords for search engines, and other information. that link i just gave you has a whole page on meta tags, but here is another little article on what meta tags are all about: http://www.webdeveloper.com/html/html_metatags.html
finally, the doctype tag your teacher was talking about. it's mainly for programs to validate your html code to see if it's correct or not. it's not required, and isn't used as much as it should be, but, basically what you're looking for is just a tag like this right at the first line of your html page:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
ok so since i have to use this meta tag... what exactly would i write? like what does the actully tag say?
ok so that daves site is freaking awsum... it helped SO much.... i finished my project! and i talked to my teacher today and i totally didn't fail... in fact, my average was like a B+ but since he told me that he knows i'm really trying, he gave me an A! i think its cuz i go to see him all the time and e-mail him with all my questions haha its good to suck up sometimes....