You are able to resend the lead welcome email to the lead at anytime. Lead welcome emails are sent automatically when the lead is entered. The resend Welcome Email button is there in case you need to resend. To get started you will want to click the Leads option in the left hand navigation menu.
You can select any lead from the lead list that you would like to resend the welcome email for.
Once the lead loads you will see a Resend Welcome Email button below the Personal Details. Once you click the welcome email it will send to the lead.
You can edit the template on the Company Offices tab in the left hand navigation menu. Once you are on the company offices page you can select the office you wish to edit the template for. Once the office loads you will see a Email Templates tab that will show you all of the editable email templates for that company office.