You can edit the campaigns that are available in LeadStreet by doing the following:
1. Access LeadStreet via Launchpad
2. Select the menu icon in the upper left hand corner
3. Choose Email Marketing
4. Choose Campaigns
5. Find the campaign that you want to edit, and select 'Edit' under the Actions drop down section
6. Make any updates you wish to make and save the changes
You can do the same for any templates available in the Message Library in LeadStreet.