"Warming up" means building up a new domain's sending reputation gradually, instead of sending a huge volume from it on day one. Whether this applies to you depends on which kind of address you're sending from.
Using a SeekaHost address
If you're sending through a SeekaHost-managed address - the default before you verify your own domain, or if you chose one during onboarding - there's nothing for you to do. That domain is already established, and you're sending through its existing reputation, not starting one from scratch.
Using your own new domain
Warming up only really matters once you've verified a domain of your own that's never sent bulk email before. There's no automatic ramp-up built into the product for this - it's on you to ease into it. The general approach: start with smaller sends to your most engaged subscribers, and grow your volume gradually over the first couple of weeks rather than sending to your entire list on day one. Inbox providers trust a domain more when its sending pattern looks established and wanted, and that takes a little time to build.