What verses encourage you to speak before a group?
The difficulty here is that not everyone is capable of public speaking. Paul explains that, like the human body, the body of believers as made up of different members with different functions. Romans 12:1-7; 1 Corinthians 12:12-25; 1 Peter 3:15
For those of us who find public speaking difficult, the best solution is to have the talk fully written out and read it. Practice will soon reveal whether we are comfortable and capable of speaking to a group.
I hope you find this helpful.