Tim posted Blocks that use the for each item in a list block in a new Button in your Project (Button2 perhaps). In order to send a message to every phone number in a list, don't you think you need to tell the Program to do something with each item in the list? Perhaps send the message.
Are you afraid of experimenting? What have you tried? Create a new Button (perhaps keep everything else the same as in your broadcast hub app). Why? Because you probably need the phone numbers that are in the existing BroadcastList block The for each item in list blocks will execute the call Texting.SendMessageDirect Block for each phone number.
Take a break . Read and do the List tutorial by Sajal which shows how to use that Block.
or do the exercises in Programming Lists of Data
Do you like puzzles? The Block scrambled puzzle is a possible solution (it also uses a Clock to space out the timing of sending the sms messages)
ALL the Blocks you need are there. You just need to place them in the proper place. Read and do the tutorials and then put the Blocks together. You need to learn to code, not merely copy Blocks...maybe the puzle will help.