If your board does not come with a display, you will need to obtain an SSD1306 display separately. The SSD1306 OLED displays are made in two different pin oderings. The preferred OLED displays have the following pin order: VCC-GND-SCL-SDA. They can be soldered into TTGO T-Beams directly. The OLED displays with the GND-VCC-SCL-SDA pin order need to be soldered in such a way that display does not get reverse-polarity on the power terminals.

This is the SSD1306 display that matches the TTGO T-Beam boards: Photo courtesy Konrad Roeder, WA4OSH

When the display has the proper pin order, the pins line up like this: Photo courtesy Konrad Roeder, WA4OSH

This tracker has a display with the preferred pin order VCC-GND-SCL-SDA soldered-on: Photo courtesy Konrad Roeder, WA4OSH

This SSD1306 display has the wrong pin order for the TTGO T-Beam boards:

Photo courtesy Konrad Roeder, WA4OSH

In order to use this OLED display, solder the OLED board onto the main board this way: Photo courtesy Konrad Roeder, WA4OSH

Photo courtesy Michael Multerer

Here's the finished product: Photo courtesy Konrad Roeder, WA4OSH