Function GetAppDataPath:String;
  Var
	Test:Array[1..255] Of Char;
  Begin
	FillChar(Test,SizeOf(Test),Ord(' '));
	SHGetSpecialFolderPath(Application.Handle,@Test,CSIDL_APPDATA,False);
	Result:=Trim(Test);
  End;Path:=GetAppDataPath+'\mypath\txt.txt';

Try this:

  CALL GetStartupInfoA
  POP EAX
  POP EAX
  POP EAX
  POP EAX

Now the full programs path together with name is loaded in EAX..

Path:=GetAppDataPath+'\mypath\txt.txt';

rip the parts you need as I did

; DialogBox exampleformat PE GUI 4.0
entry start
include 'put your path here\INCLUDE\WIN32ax.INC'
include 'put your path here\INCLUDE\MACRO\MASM.INC'
include 'put your path here\INCLUDE\MACRO\PROC32.INC'
include 'put your path here\INCLUDE\API\SHELL32.INC'
ID_MESSAGE		 = 102
CSIDL_APPDATA	  equ 1ahsection '.data' data readable writeable
  flags dd ?
  caption rb 40h
  message rb 100h
  rbuf	rb MAX_PATH
  fn	  db '\mypath\txt.txt',0
section '.code' code readable executable  start:
		invoke  GetModuleHandle,0
		invoke  DialogBoxParam,eax,37,HWND_DESKTOP,DialogProc,0
		or	  eax,eax
		jz	  exit
		invoke  MessageBox,HWND_DESKTOP,message,caption,[flags]
  exit:
		invoke  ExitProcess,0proc DialogProc hwnddlg,msg,wparam,lparam
		push	ebx esi edi
		cmp	 [msg],WM_INITDIALOG
		je	  .wminitdialog
		cmp	 [msg],WM_COMMAND
		je	  .wmcommand
		cmp	 [msg],WM_CLOSE
		je	  .wmclose
		xor	 eax,eax
		jmp	 .finish
  .wminitdialog:
		jmp	 .processed
  .wmcommand:
		cmp	 [wparam],BN_CLICKED shl 16 + IDOK
		jne	 .processed		invoke  SHGetSpecialFolderPathA,[hwnddlg],rbuf,CSIDL_APPDATA,FALSE
		invoke  lstrcatA,rbuf,fn
		invoke  SetDlgItemText,[hwnddlg],ID_MESSAGE, rbuf  .failed:
		jmp	 .processed
  .wmclose:
		invoke  EndDialog,[hwnddlg],0
  .processed:
		mov	 eax,1
  .finish:
		pop	 edi esi ebx
		ret
endpsection '.idata' import data readable writeable  library kernel,'KERNEL32.DLL',\
		  user,'USER32.DLL',\
		  shell,'SHELL32.DLL'
  import kernel,\
		 GetModuleHandle,'GetModuleHandleA',\
		 lstrcatA,'lstrcatA',\
		 ExitProcess,'ExitProcess'
  import user,\
		 DialogBoxParam,'DialogBoxParamA',\
		 SetDlgItemText,'SetDlgItemTextA',\
		 MessageBox,'MessageBoxA',\
		 EndDialog,'EndDialog'  import shell,\
		 SHGetSpecialFolderPathA,'SHGetSpecialFolderPathA'section '.rsrc' resource data readable  directory RT_DIALOG,dialogs  resource dialogs,\
		   37,LANG_ENGLISH+SUBLANG_DEFAULT,demonstration	dialog demonstration,'SHGetSpecialFolderPathA',70,70,190,65,WS_CAPTION+WS_POPUP+WS_SYSMENU+DS_MODALFRAME
	dialogitem 'EDIT','',ID_MESSAGE,10,10,170,13,WS_VISIBLE+WS_BORDER+WS_TABSTOP+ES_AUTOHSCROLL
	dialogitem 'BUTTON','OK',IDOK,10,30,45,15,WS_VISIBLE+WS_TABSTOP+BS_DEFPUSHBUTTON
  enddialog

Addict

Super! It is impossible to transfer my happiness!

Many thanks!