>But I don't want the input text having the HTML effect when it display, (even users have type HTML tag into the input box, then the screen only display same thing(not HTML effect) they type after they post it).

The following will remove any tag from an HTML block for such a need:

* Remove all tags from an HTML text
* expC1 Content
FUNCTION ExtractTag
PARAMETER tcContent
LOCAL lnStart,lnStop
lnStart=1
lnStop=0
tcContent=ALLTRIM(tcContent)
DO WHILE lnStart>0
   lnStart=AT('<',tcContent)
   lnStop=AT('>',SUBSTR(tcContent,lnStart))
   IF lnStart=0 OR lnStop=0
      EXIT
   ENDIF
   IF lnStart=1
      tcContent=SUBSTR(tcContent,lnStop+1)
      ELSE
      tcContent=LEFT(tcContent,lnStart-1)+SUBSTR(tcContent,lnStart+lnStop)
   ENDIF
ENDDO

* Now, for all the rest, we need to make sure, that we don't have a single < in the string
tcContent=STRTRAN(tcContent,'<','<')

RETURN tcContent