You will have messages constructed using the information you provide and dispatched to your regular text messaging app. The app would giving you 7 seconds to dispatch each message otherwise it may save it as a draft.
An example: If you want to send the same sms to Evans with number 0234908361 and to James with number 1234567890; You have to type the salutation, and the message then select the contacts you want to send the message to (in this case Evans and James). The app will pick the saluation, append the name Evans, a comma is then appended and the message follows. If you saved the name as say EvansOne, you are allowed to edit the name to say Evans. You then click the send button. The app would then send the message to your regular text messaging app and give you about 7 seconds to dispatch the message otherwise it may save the message as a draft and move on to display the constructed message for the next contact (in this case James).