At the airport: Boarding at the gate

💬 [C'est] is the fixed way to say "it is / this is" before a noun: [C'est la porte B12], [C'est mon siège], [C'est ici]. You do not say [Il est la porte B12] for this kind of identification.

💬 French often uses [pour] to mean "for" in the sense of destination or assignment: [un train pour Lyon], [la porte pour Paris]. It is not about purpose here, just which flight or route something belongs to.

💬 [C'] in [c'est] cannot stand alone; it has to be attached to the next word. You will see the same joining in [c'était] and [c'est bon].

💬 For "going to" a place, French uses [aller à]: [tu vas à Paris ?], [je vais à la porte B12]. The verb [vas] here comes from [aller], so it does not look much like the basic form.

💬 [Aussi] usually comes after the thing it adds to: [Paris aussi], [moi aussi], [ma carte d'embarquement aussi]. English often puts "too" at the end, but French is a bit more flexible.