How does texting from a cell to update one’s twitter account work?

Question From User - Answers in Comments.
Since I don't text often, I have the 250 txt per month plan with att. If I submit my cell # to Twitter, will I be able to txt a tweet to Twitter without getting any updates from other people. Can I just tweet but not have twitter txt me with updates the people I follow post? Will the txt still count as part of my plan or will it be a different charge? Hope my questions are clear.