What if I forgot to cvs checkout?

[laredotornado]

Hi,

I'm new to CVS and just downloaded the latest version and installed it
on my Fedora Core 5 Linux system.  I have created my project in CVS,
with module name "myproj".  My question is, let's say I forgot to
checkout the files, then I edit a file and want to commit.  If I try
and checkout at that point, won't the checkout process overwrite my
newly-edited file?  Thus, how do I check that file (and others) in?

Thanks, - Dave