Writing to my Elegoo Uno with Arduino software

Hi. I recently got an Elegoo Uno and they say it's 100% compatible with Arduino. So, I downloaded the Arduino software to make a sketch and tried to upload it to the Elegoo Uno board. I verified the sketch and it has no errors, but it gives me an error when uploading "Problem uploading to board." As I expected, when I click on Serial Monitor it says "Board at COM1 is not available." However, the board is plugged in and the green light is on, and the computer only has one USB port.
So why is it not connecting?

Can you select a port in the IDE ?

Tools->Board->Arduino/Genuino UNO
Tools->Port->whatever serial port your board is connected to

If you use the IDE you will have to choose the port yourself I deed.

If you is the online version, create.arduino.com it wil choose the right one MOST of the times. If not you'll find it pretty easy whee to choose the right