vbulletin imacro

hey guys lookingto create a macro that can automise mailing users on a vbulletin forum

struggling to get the macro to go through the id's in order to pm.

basicly heres the structure of vbulletin forums

heres link to a profile "member.php?u=357850" as you can see each profile has a unique id in this case this user is "357850"
i was basicly wondering how ican make the macro go through each id starting from 1-random number of my choice

so basicly the macro will go to

member.php?u=1 (user profile)
then will auto go to the "send message link
which is like this
private.php?do=newpm&u=1

enter text i wish then move onto the next id which will be
member.php?u=2
private.php?do=newpm&u=2

hope u understand what i meen.basicly just want it to edit the ID and add 1 extra number so i can basicly mass message every user.