Hello, as resident alien for texes since october 23, I could not add my 1042-S form code 19 in my return. should I mail it directly to IRS?

Because the 1042S is a Non-Resident Alien form, the form itself is not supported.  It is entered as Other Reportable income if this was income received while you were a RESIDENT ALIEN.  This means, code 19 is not really relevant since as a resident alien you are subject to taxation the same as a US Citizen, so you do not need to mail it directly to the IRS for any sort of special tax treatment.

If this was for income received prior to becoming a resident alien, then you may need to report it on your 1040NR if you are filing as a Dual Status Alien for the year.  

@cecilia08901 , I don't know if you still need help on this.  I agree with my colleague @Vanessa A  that 1042-S needs to be recognized and generally  with an eye to when your residency began.

What we need is to understand how you became a resident for tax purposes .  I ask this because   your residency  is generally determined  by passing  SPT ( Substantial Presence Test ).  Once you pass the SPT, you are resident for the calendar year. While the end of the year ( 12/31/XXXX) is fixed ,  the start of the year depends on your first day of presence in the country taking into account your visa status.   See this :

Residency starting and ending dates | Internal Revenue Service (irs.gov)

Does this help ?