I don't have temphls.inc on my computer but...
try this
include \masm64\include64\masm64rt.inc
.code
WinMain proc
invoke MessageBox ,NULL, addr MsgBoxText, addr MsgCaption, MB_OK
.if rax == 0 ; or did you really want eax here?
.if rax } 0 ; in masm64 use'}' in place of '>'
;; put you statement here
.endif
.endif
invoke ExitProcess,NULL
WinMain endp
MsgCaption db "Iczelion's tutorial #2",0
MsgBoxText db "Win64 Assembly is Great!",0
END