When using a Signal Tower with an EXP Brain, you will have to configure the Signal Tower like you would any other device. Once a Signal Tower is configured, the Signal Tower's commands will be added to the Toolbox.
Open a project in VEXcode EXP.
Select the Devices Window icon in the top right corner of the screen.
Select the Add a device button.
Select SIGNAL TOWER from the list of available devices.
Select which port the Signal Tower is connected to on the EXP Brain.
Once you have selected a port, it will turn green.
Now, you can rename your Signal Tower to whatever you want. This will be used in all blocks and commands for this Signal Tower.
Select Done.
Signal Tower commands will appear in the Toolbox, allowing you to begin coding the Signal Tower in VEXcode EXP.