next step in contributing to Debian

[Nicholas Steeves <nsteeves@gmail.com>]

Hi,

I've finally gotten comfortable with pbuilder (for both i386 and amd64), 
and have done a number of private backports (including Intel 2015Q2 
graphics stack) and imports of Ubuntu packages that don't exist in 
Debian (eg: snapraid).

Just the other day someone in #debian asked for a backport of 
xserver-xorg-video-savage, so I built an unofficial one on the spot.

What's the next step in contributing?  What version should I be putting 
in the changelog.  For xserver-xorg-video-savage_2.3.8-1, backported to 
jessie, it seems like it should be:

xserver-xorg-video-savage_2.3.8-1+nmu1~bpo8+1

So, package-name_version-revision+non_maintainer_upload(X)~backport(Y)+(Z)

Y is the Debian version the backport is for, but what is X and Z? Also, 
for NMUs, will I need to sign anything with GPG?

Thanks!
Nicholas