I'm creating many different web apps with Laravel 5 like an e-commerce, a blog, etc... All of my web apps need a login so I must secure my routes (mostly the ones like an e-commerce app) but I don't really understand how the SSL certificate works and how to apply them...
You should probably manage HTTP to HTTPS redirects at server level, not code. That way, all requests will be HTTPS, just have to make sure links/resources etc are linked via HTTPS.