Ok this is the one thing that is bugging me...

The FAQ said to add the path of your nshulls.txt file to your command parameter or something.

Can someone please give me a more detailed explanation of this?

When you compile your map, the first program you or your batch compiler starts is hlcsg.
For example:

"C:\Programme\eddi's Tools\ZHLT Compile GUI\ZHLT\HLCSG.EXE" C:\mymap.map

To fix the onos problem, you have to add

-hullfile <path to your ns directory>\nshulls.hul

for example

"C:\Programme\eddi's Tools\ZHLT Compile GUI\ZHLT\HLCSG.EXE"
-hullfile C:\Steam\Steamapps\mygreatsteamaccount\Half-Life\ns\nshulls.hul C:\mymap.map

Where do I add that at? I've tried googling my problem and I don't understand where to put the command line at!

can you like show me a picture or something?

If you're using a batch compiler, do what bERt0r says.

If you're using hammer's GUI to compile: press the run map-icon(3 white cogwheels). If you've set hammer to show advanced compile options you'll see a bunch of lines of text with check-boxes beside them. Find the one that says $csg_exe $path\$file and click on it(text not check-box). In the parameters edit-box above you'll see $path\$file add -hullfile <path to hullfile>(e.g mine is $path\$file -hullfile "f:\\vhammer\\ns\\hulls.txt" -chart, chart adds some info).

Ah thanks!

I was able to do it with the batch compiler...I never used it before so I didn't know what I was doing but it's all good now.

you need Batch Compiler and in the CSG tab you can browse your nshuls.txt