Template talk:Welcome

How to use the template
Just type on a user's Talk page. As soon as you Save, the entry will lose its link to the template and become ordinary text, which you can edit to personalise it.

Use of "subst:" prefix
Using the prefix before any template name copies the template then cuts the connexion. If you omit the "subst:" the result copies just the same but will not be editable and will always show the current version of the template - probably not a good idea for a one-off welcoming message although it is useful for many other templates.

Make another one just for you to use
On your user page you could create a link to something like template:WelcomeJG then make the resulting page a copy of template:Welcome and modify it any way you like. Then you can type or paste on a newcomer's page and not need further personalising.