[paegus]

click on 'Get Source' and save that file to your local sourcemod extraction's .../sourcemod/scripting/ folder.
click on hidden.inc and save that similarly to the .../sourcemod/scripting/include/ folder.
click on weighter.phrases.txt and save that to .../sourcemod/translations/
if you're using windows, go into the scripting folder and double click on compile.exe to compile all the .sm files in that folder.
if you're using linux run ./compile.sh.
the resultant .smx file will be in the .../sourcemod/scripting/compiled/ folder.
copy that to the server's .../addons/sourcemod/plugins/ folder
execute sm plugins load hsm_weighter on the server's console