Hey there Luis,
It stands to reason that if you don't have a phone number in order to send text messages, then you wouldn't be able to send them. iMessage is an Apple feature, and it allows messages to be sent to other devices that also have iMessage.
With the above in mind, we see you're using an iPhone XR, which would've come with a phone number when you purchased it, or you can obtain one from your carrier, so we're a bit confused as to what exactly is happening.
If you're unable to send SMS messages(green ones), not iMessages(blue ones), from your iPhone, then the next steps to take would be listed here: If you can't send or receive messages on your iPhone or iPad Please keep in mind that the steps also include contacting your carrier.
Cheers!