GREAT ADVICE from Richard Carlton on scaling a FileMaker database to a 100 users. He lists very specific steps–reduce calculations and portal sorting, for example–that will improve performance as the user count increases.
Making a database that can work with 100 simultaneous users is not something that is easily done for a novice developer. We have given you a good start in the right direction with FM Starting Point 4. This video provides a bit more direction on the topic.