1) Open an empty InfoSWMM project. Do not initialize it.
2) Save the project as MY .MXD within the folder where you have MY. ISDB
3) Initialize the project.
4) Click the reset Display button
That should create the project for you. If you want an H2OMAP SWMM project, you can save the InfoSWMM model, and then Import it from H2OMAP SWMM.