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 :