Hi @arduinoelio
welcome to the arduino-forum.
You started a hobby that can be very fascinating.
From your question I conclude that you really really just started.
There is everything right with having just started.
Post the code that you have found that does
Post this code as a code-section like described here
There is a part of the code that reads in the altidute-data from the BMP280 sensor into the arduino.
Then there is another and different part that sends the data from the arduino to the computer / serial monitor
best regards Stefan