Help Custom Text Tones?

[TheBrightStar6]

Okay, I just bought a Samsung Galaxy Android 551 phone a few days ago. I have an SD card that has tons and tons of songs and short tunes and all that on it. I managed to get a ringtone from it onto my phone, but I don't know how to put custom text tones on.

Do I actually have to download text tones, or can this phone not use custom text tones AKA I have no choice but use the text tones the phone came with?

Thanks!