How do you say I have to tell something in sign language?

There isn't a single sign in American Sign Language (ASL) that directly translates to "I have to tell something." You'd need to use a combination of signs depending on the context. Here are some options:

1. "I need to tell you..."

* "NEED" (sign for need) + "TELL" (sign for tell) + "YOU" (sign for you)

2. "I have something to tell you."

* "HAVE" (sign for have) + "SOMETHING" (sign for something) + "TELL" (sign for tell) + "YOU" (sign for you)

3. "I must tell you..."

* "MUST" (sign for must) + "TELL" (sign for tell) + "YOU" (sign for you)

4. "There's something I need to tell you."

* "THERE" (sign for there) + "SOMETHING" (sign for something) + "NEED" (sign for need) + "TELL" (sign for tell) + "YOU" (sign for you)

5. "Important thing I need to tell you."

* "IMPORTANT" (sign for important) + "THING" (sign for thing) + "NEED" (sign for need) + "TELL" (sign for tell) + "YOU" (sign for you)

It's important to use appropriate facial expressions and body language to emphasize the importance or urgency of the information you're about to share.

Remember, ASL is a visual language, so you'll need to show the signs clearly and use appropriate body language to convey your message effectively.