When I write I have to hold the letter!

Hi: I am a new Mac people, I am try to configured my new laptop and now when I going to write nothing happen, after being looking for a solution I find that when I hold the letters, then appear. No one can write like this! I don't know how to fix it, and I don't have time to go to the store for tutoring, but in need to work in the computer, I am student, so I hope that any body here can help me. Thank you!