(You should not try to drive LEDs directly from Ard pins without resistors.) Since you haven't tinkered with electronics before, you want the "Getting Started with Arduino" book. Maker Shed MBK1.

Arduino has shrunk the UNO R4 with the Arduino Nano R4 board equipped with the same 48 MHz Renesas RA4M1 32-bit Arm ...

This Arduino Get Started guide shows you how to set up a capacitive soil moisture sensor with an Arduino. Like many Arduino sensors, soil moisture detectors only have three pins: GND, VIN, and data.