I have installed NS and i have no idea how to play it or register it on steam can some1 plz tell me what to do....BTW HL1 does work

So you already properly installed HL1 on steam and installed NS? Alright, if you did everything right then just rightklick the steam symbol in the lower right corner (beside the clock), klick on "games" and there you should see NS1. If not, you probably installed something wrong...


edit: You can register HL1 on steam by opening the steam window, go under "games" and then "activate a product on steam". There you enter your HL1 cd-key. Done :D. Now you can install NS.

well, not just that :P
after registering the product, then you need to install it and play it once (just fire up the hazard course), THEN install NS.

do you still need to restart steam too?

only after installing half-life and ns...