On the top bar of the page, how do you get the welcome message with the X to close it?
Welcome to the Question2Answer Q&A. There's also a demo if you just want to try it out.
Now I've got 1.5 installed on my machine I can answer this. The option is under Admin > Users. Tick "Notice at top for first time visitors - HTML allowed" then put your message in the box.
Welcome to the Q&A site for Question2Answer.
If you have a question about Q2A, please ask here, in English.
To report a bug, please create a new issue on Github or ask a question here with the bug tag.
If you just want to try Q2A, please use the demo site.