I am more than happy to answer questions that are difficult to find the answer (or to figure out) on the Help files or the Vegas Pro manual, or questions that are not mentioned in these documents, or that are mentioned in these documents but are not clear.
But answering this question to you, which is possibly the second most important editing action and therefore easy to find on the Help files (second, after the splitting action), it just shows me that you didn't bother to look for your answer at all, you just piggyback on us.
While I am sure someone will reply to your question, I won't. And google the term "RTFM" if you don't know what it is.