i Need help with car modeling

[mrhahn98]

i'm modeling a nissan 350Z ,i used meshsmooth ,but i dont know how to make some edges sharper ,some peoples tell me that i need to use chamfer on the edges i want to make it sharper and do some ....weld stuff ,but i dont know how to do it !!!! please help ,there are some screen shot .

BTW ,i want to create a hole on that front bumper (look at the images and you will understand ) i've tried to move edges in side but they only have face at the bottom (i've used 2side in material and in view ports ,but that doesnt show the surface ,the only way to see it is look from the bottom)

if someone can help me with this ,i can send the file to you so you can guide me how to do those stuff
sorry for my bad english

This is the front view before i change anything
http://img.photobucket.com/albums/v150/Keikan/ok4.gif
and everything messed up when i chamfer on those edges
http://img.photobucket.com/albums/v150/Keikan/ok3.gif
http://img.photobucket.com/albums/v150/Keikan/ok2.gif
i noticed a lot of vertices that i need to weld....
http://img.photobucket.com/albums/v150/Keikan/ok1.gif
but i dont know which one ?
http://img.photobucket.com/albums/v150/Keikan/ok.gif