C compile question

[Fabio Miranda]

Hi, I am a FreeBSD-3.2 user and I want to know why is
the best way to compile C code?, i use this way:

gcc -Wall -o outputname inputname

But, using this way i havent compiled any file, always
i got an error. 
Only, i could compile successly some port collection
program, but no more.

Can any one tell me what do i need to compile C code
on my system?, do i need extra includes ? where can i
get them?

thanks
__________________________________________________
Do You Yahoo!?
Thousands of Stores.  Millions of Products.  All in one place.
Yahoo! Shopping: http://shopping.yahoo.com