Open the chat and at the bottom right you have a button "spammer" press-it and you have this menu :
Command: The command
Tick to wait: 1 tick = 1/20s
Number: Number of iteration of the command
You can also use the /spammer command :
With your command to spam you can now put some arguments : (/spammer optionslist)
For example with the command "say Hello my name is &pname and I have &hp hp" you have :