hello guys, i'm making a note app for tablet that is in portuguese for now, but my biggest question is how can i save in .txt on internal storage
What do you mean by "sdcard"?
If you mean a removable (mircro) SDcard you can't, because since Android 4.4 (KitKat, API 19) this is read-only.
See also here:
sorry for my mistake, it was for the internal storage, i just literally forgot the internal name and people usually say sdcard
Show your blocks (as mentioned in my guide "How to ask a question ...").