Hi, 

You can download a free demo license which is valid for 45 days or you can generate a developers license (requires an account on EPiServer world) here: https://license.episerver.com/

When you receive the license by e-mail, you need to put it in C:\EPiServer\Sites\MyEPiServerSite (ref the error message you received). 

Karoline

By default none of the sample sites deployed via Deployment Center does not contain license file. You have to order and then copy over to your site manually. Licenses are available here - https://license.episerver.com/