The first way is to call up an instrument on a channel like you would any other time, such as @0. Then use the n command to make that instrument use noise.
This calls up instrument 0 and then tells that instrument to play noise at frequency 1F (numbers are in hexadecimal and go from 00 to 1F with higher numbers representing higher frequency noise). The instrument's initial settings like volume envelope are still preserved. From there, you can put notes on the channel like you would with any other instrument. Only difference here is that with noise, all notes sound the same. To change the noise pitch you can use another n command, and to go back to using a sample, simply call another instrument. You can also call the same instrument which you previously put noise on to restore it back to its initial settings.
The second way to do noise is to actually make an instrument which uses noise by default. This is handy if you're going to be using noise a lot while simultaneously doing a lot of instrument switching. Basically when creating a new instrument, instead of putting in a sample name or a previous instrument number to start, you simply use the n command like above. After that come normal instrument setup parameters. For example:
n1F $Df $78 $7f $01 $00
That was copied strait from a port I'm working on so it'd better work Also the last two bytes, the tuning multiplier and submultiplier afaik don't have any effect when using the noise.
I also encourage you to look at the readme, as it details this and other related topics more. If you need more help with things, let us know.
Make more of less, that way you won't make less of more!