Article 389.4 of the Criminal Procedure Code gives 15 days to appeal, counted from the day the verdict is pronounced. For a defendant held in custody the period runs instead from the day a copy of the verdict is served on them. That distinction matters for foreign nationals: if the verdict was served late, or served without a translation your relative could read, the clock may not have started when you were told it did.
A missed deadline can be restored under Article 389.5 where it was missed for a valid reason. Late service, absence of an interpreter, and hospitalisation are all recognised grounds. The application goes to the court that gave the verdict.
The appeal itself is filed through the trial court, not directly with the appeal court. Filing it in the wrong place wastes days you do not have.