1. "Text": Sign the sign for "write" (the sign for "text" is a more recent invention not universally used).
2. "Me": Sign the sign for "me".
You can also add context by signing the person's name or the topic of the text message after signing "write."
For example:
* To sign "Text me about the party": You would sign "write" (for text), then "me", then "party".
* To sign "Text me later": You would sign "write" (for text), then "me", then "later".
Remember, ASL is a visual language, so using facial expressions and body language will help convey your message clearly.