For the "schedule expression" (the * * * * * part), try https://crontab.guru/. Some distributions have shortcut expressions like @hourly or @daily so you don't have to type * */1 * * * etc.

The crontab generally has a header that shows the columns, but if not, they're: m h dom mon dow command.

From * * * * * /usr/bin/sct 2750 I'm guessing you want to run every minute. If that's the case, as another commented pointed out, try */1 * * * * /usr/bin/sct 2750, meaning every 1 minute.

OK... So, just to test, edit your crontab and run a basic command:

*/1 * * * * date >> ~/date.log

this will append the current date/time once a minute (*/1) to a file in your home dir. You can check if it works with cat ~/date.log

If that works, then try again with your command. I see you used the full path to it, that's a good thing. Also, what does that command do if you run it manually?

To run the command at 10 PM every day, you should have it like this:

0 22 * * * /usr/bin/sct 2750