The DS1302 uses a 3-wire synchronous serial interface. You can connect it to any three digital pins on your Arduino, but common practice uses pins 2, 3, and 4.
The VirtuabotixRTC library is exemplary in its minimalist design. It provides only the essential functions needed for basic RTC operations, which contributes to its small memory footprint—an important consideration for ATmega328P-based boards like the Arduino Uno with limited SRAM. virtuabotixrtc.h arduino library