I am a newer here.
I just want to insert some words in the video, such as "copy right at qiushukun1234". I saved these words in a text file. then i click the icon of open original subtitles file, and insert that file. what should i do next step? Please help

Well, I'm not certain what you want to do... if you want to put copyright in the movie, you need completely different program than ST (or don't need a program at all, Win should suffice). Get some TAG editor (abcAVI Tag Editor is the best I know) and edit the video file.

If is a MicroDVD-type subtitle, at the end or begining, insert a line like this:
{150000}{150100}Copyright...........
150000 and 150100 must be valid number of frames of the movie. Replace those values with something a little more than the last line of the subtitle:
This is the last line, for example:
(145320}{145400}Goodbye my frend, I'm dying.
Then you add the line:
{145450}{145550}Copyright........
If is not a MicroDVD try converting it.