I bought this (https://www.ebay.com/itm/5V-RFID-Reader-Writer-Wireless-Module-125KHz-EM4100-8CM-UART-3Pin/123144599463?hash=item1cabfd77a7:g:hjYAAOSwx8pa5X7Q) 125khz reader and writer for my arduino but discovered there was little interfacing information that was easily understandable. If there is a library that would work, thats is great. Otherwise, how can I use this board? I have an arduino nano and uno if that helps.
There is a description of the interfaces and output on the eBay site. There are two interfaces, Wiegand and TTL/RS232.
The latter can be read using the Arduino serial port, or using AltSoftSerial or the like. Consult the Serial Input Basics tutorial for guidance.
If this is your first project, we strongly recommend to start with the examples that come with the IDE (blink an LED, read a button, a voltage or a temperature sensor) in order to learn the language and the special features of the Arduino. If you don't, expect endless frustration.
a) Please link to the datasheet of that reader and/or link to libraries you found for that reader.
If you haven't found something so far, consider to buy another reader.
b) Please describe or link to the target you want to read.