Put in the texture, then in the worldspawn entity define the cl_skyname (i think it's called that) to the name of the sky texture, for example "space".
You'll have to do a search for the list of Half-Life's default skyboxes however. But that's how you do it <!--emo&:)--><img src='http://www.unknownworlds.com/forums/html/emoticons/smile.gif' border='0' style='vertical-align:middle' alt='smile.gif'><!--endemo-->
Esuna's right. Here's a list of the skies that come with HL.<ul><li>2desert <li>alien1 <li>alien2 <li>alien3 <li>black <li>city <li>cliffe <li>desert <li>dusk <li>morning <li>neb1 <li>neb6 <li>neb7 <li>night <li>space <li>xen10 <li>xen8 <li>xen9 </ul>
All of the skies that came with HL can be used in NS, just put name as I listed it in the field in worldspawn. There are some skies that came with NS though I would recomend you ask the mappers who made the skies if you could use it. They are :<ul><li>eclipse_ <li>lost_ <li>mars_env <li>mars2 <li>mars <li>td2 <li>uwat_ </ul>
Comments
You'll have to do a search for the list of Half-Life's default skyboxes however. But that's how you do it <!--emo&:)--><img src='http://www.unknownworlds.com/forums/html/emoticons/smile.gif' border='0' style='vertical-align:middle' alt='smile.gif'><!--endemo-->
<li>alien1
<li>alien2
<li>alien3
<li>black
<li>city
<li>cliffe
<li>desert
<li>dusk
<li>morning
<li>neb1
<li>neb6
<li>neb7
<li>night
<li>space
<li>xen10
<li>xen8
<li>xen9
</ul>
I tried adding a sky, but it has an error saying that it couldn't find/load it and it adds rt after the file name...
<li>lost_
<li>mars_env
<li>mars2
<li>mars
<li>td2
<li>uwat_
</ul>