Does STM32CubeMX assist in creating STM32L0 firmware for communication with smartcards?
As mentioned earlier, STM32CubeMX creates a project directory and generates all the files you need to set up the peripheral pins and clocks.  In addition, the Cube generates files for the HAL (Hardware Access Layer).  

In terms of using the TX (which I am thinking you mean UART?), you could use the HAL functions to use the UART.  

[Conversely, you could write your own functions and set registers but the path of least resistance is to use their library, which is what I am sensing is the goal here?].

The HAL is a whole bunch of source files and headers that STMicro wrote, that allows you easy access to set the UART configuration you need and then send actual data out of the UART.

Here is a link to a STM HAL UART TUTORIAL showing you the basic usage of the STM HAL for UART.

There's definitely a learning curve, to seeing how all these pieces link up.

Once you are sending data from the UART TX pin, hook it up to your smartcard and than you get to read the smartcard documentation on how to commnicate to it.

Good luck, you'll learn a lot if this is your first time doing this.