Unless you are using a preamp for your mic you will
not have any gain so
the only way you can get sound in is to shout very loudly
Some sound cards do have a 1/8 inch microphone jack which works with dynamic
mics. If it's marked as 'mic' rather than 'line' then it could be the
right
level input. Try your mixer application (eg aumix or alsamixer) to see if the
mic channel is selected as an input, or has been muted.
Cheers
Daniel