Well ... first u have to download the .sma file from a zombie class.
Open it with Amx Mod X Studio, i u want to change settings.
( With ZP 4.3 u can even change some settings in zp_zombieclasses.ini
I would prefer to change models etc. in that file, cause its much easier than re-write the original plugin )
After u have changed some Settings, like speed, hp and so on u have to compile it in .amxx
If u have downloaded amxx, u will now have the folder amxmodx, go to folder "scripting" .. there u will find the AMXXPC compile.exe or just compile.exe
Just put the .sma on that icon and it will automaticly compile.
Your compiled zombie class is now in scripting -> compiled folder.
Now open ur ftp client and put this file in cstrike/addons/amxmodx/plugins
After you have done that, go to folder cstrike/addons/amxmodx/configs and open plugins-zplague.ini
There u add your amxx zombie classes file name, ill show u an axemple:
; - Quick tips -
; * Rename this file to disabled-zplague.ini to turn the mod off
; * Rename it back to plugins-zplague.ini to turn it on
; * Put a semi-colon in front of a plugin to disable it
; * Remove a semi-colon to re-enable a plugin
; * Add the word debug after a plugin to place it in debug mode
; Main plugin
; Default zombie classes
; Add sub-plugins, custom zombie classes, and extra items here
; Zombie Classes
;zp_zclass_warlord_zombie.amxx <- with ; in front u disable a class
Now restart your server or just change map and the new zombie class will be loaded !