John,

>How to use APPEND FROM to import the 300 characters to memo field?

If each line contains only the memo field content:

create cursor temp1 ( c1 c(254), c2 c(254) )
append from TheTextFile.txt type sdf
select temp1
scan
   if empty( c2 )
      insert into FinalResult ( TheMemoField ) values ( rtrim( c1 ) )
   else
      insert into FinalResult ( TheMemoField ) values ( c1 + rtrim( c2 ) )
   endif
endscan