How do I get sounds in my maps?

I am trying to get sounds in some of my maps but I cant seem to figure it out. Could some one point me to a detailed tutorial or explain it to me in detail? I would appreciate it. I always here cool sounds in other maps like computers humming or birds in outdoor areas and thats what I want. Thanks in advance.

Do you want custom sounds or to use the ones that come with halflife?

http://cariad.co.za/twhl/entityinfo.php?ent=ambient_generic&game=1

http://collective.valve-erc.com/index.php?ent=ambient_generic

Use pakexplorer to browse to the sound folder of your .pak file. This
allows you to get the names of and listen to the sounds. Then just
enter the sounds name into the box in the ambient_generic and away you
go.

I wouldn't mind using both. Will pakscape work also?

For custom sounds just put the sounds you want to use in the
valve/sounds folder. Replace valve with whatever mod you're mapping for.

Here is a tutorial to convert custom sounds to play in halflife:
http://www.snarkpit.com/editing.php?page=tutorials&game=HL&id=98

Use the ambient_generic entity, but remember you need the sound in the correct format. So I would also suggest reading this tutorial as well: http://www.snarkpit.com/editing.php?page=tutorials&game=HL&id=98 and also this:
http://www.snarkpit.com/editing.php?page=tutorials&game=HL&id=97 Hope that helps!

Here's a big pack of sounds pre-formatted for use in Half-Life:

http://www.cryotank.net/maps/textures/jinxsounds_v2.zip