Intro to Arduino - this is an excellent resource that includes a glossary of what many of the programming terms actually mean.
Here, you will see two excellent Arduino Legacy Projects. The first one is a very basic introduction. I recommend reading through the ENTIRE first presentation before getting out any equipment. As you read, YOU WILL HAVE QUESTIONS. There may be parts you find confusing. But, as you CONTINUE TO READ, many of the answers will become clear. Do not get stuck on one slide of the presentation because you are confused. Keep reading, and it is likely that your questions will be answered.
AFTER READING THROUGH THE FIRST PRESENTATION, you should be able to start programming.
Troubleshooting
Select board and port in Arduino IDE - click this link for some guidance on how to do this.
The board selection tells Arduino IDE how to compile the sketch and what protocols to use when uploading the sketch. In some cases, it will be automatically set, but it can be overridden with the Tools > Board menu or in the “Select other board and port…” dialog.
The port selection refers to an actual board (or other device) that’s connected to your computer. Many boards are automatically recognized by Arduino IDE—these boards will have their name displayed next to their port in the Tools > Port menu and will have their port associated with the identified board in the board selector menu.
Windows enumerates a new different COM port for every serial number or VID/PID detected. Also, a new COM port will be enabled if the device is connected to a different physical USB port. Therefore, the same device on the same port can have different COM port numbers depending on the its functioning mode or the USB port it is connected to.