When you use real-time recording (which is what you are doing), NWC needs some pre-existing music to play, so that it can tell how long your notes are.
The easiest way is to create a temporary new staff with a simple drum beat. Don't forget this should be channel 10. Add one
bar of simple beats, then copy and paste until you have more than enough. To speed things up, after you've pasted a few times, copy everything so that you are pasting multiple bars. You can repeat this short-cut, and in no time you'll have what you need.
When doing real-time recording, I find it's really good to slow things down, to much slower than the required tempo. Insert a tempo mark at the beginning, for the speed you want to record at.
You might find after a while, the first part of the recording is good, but you want to add more at the end. NWC always wants to start at the beginning, so insert a very fast tempo marking (dotted
minim = 750) is
very fast, then a few
bars before the end, insert your slow tempo marking.
The other thing to remember, is that you can build up a score. For piano, I usually play in just the left hand first. When there are multiple rhythms on the same staff, I try to get the busier one first, and then just add in the other notes in the normal note-entry ways. For larger groups, I try to do the bass first.
Once you have enough parts recorded, you can turn off the drum track - or even delete it is it's not needed.
One last option - if you're going to have a complex drum track anyway, it might be easier to notate it in full first (as there are often repeated bars, which you simply copy and paste), and use your final drum track instead of the artificial one.