There are 2 ways of doing:
1) the method using GUI scripting: this is what you've started to do. You simulate keyboard events like a user. It is not recommended for mainly 3 reasons: It is usually slow (you need to add delays to leave time for system open window, close them,..). During the script, if user hits key/mouse by mistake, your script will fail. And finally, you're hardly dependent of user interface of the application: if the editor (here Apple with TextEdit) changes something, like a short cut key, your script will no longer work.
Despite that, if you still want to use that way, here is the script that does it for you. I recommend that you add comments as I did (how to remember that key code 8 is 'c' !). I added some extra options to select the path to save (go home folder, enter special path,...). Up to you to use them or not:
tell application "TextEdit"
activate
tell application "System Events"
key code 126 using command down -- command up (cursor at start)
key code 125 using shift down -- shift down (select 1st line)
keystroke "c" using command down -- command C (copy)
keystroke "s" using command down -- open save dialog
delay 0.5 -- to let save as dialog time to open
keystroke "v" using command down -- paste the title from clipboard
-- other options
-- keystroke "h" using {command down, shift down} -- go home directory
delay 0.5
keystroke "g" using {command down, shift down} -- go to dialog
delay 0.5
keystroke "Desktop/Sample" -- path from Documents folder to Sample folder on Desktop
delay 0.5
keystroke return -- close the go to dialog
delay 0.5
keystroke return -- close the save as dialog
end tell
end tell
2) the method using Applescript instructions. It is usually much shorter, more elegant script, much faster to run, and user can't break it during execution. The script bellow does same as script above: It selects the first text row and save the document with that title. Line 1 defines the folder where to save:
set myPath to (path to desktop folder) as string -- path where to save file
tell application "TextEdit"
activate
tell front document
set myTitle to first paragraph
set myTitle to text 1 thru -2 of myTitle -- to remove the return at end of paragraph
save in (myPath & myTitle)
end tell
end tell
I hope it helps