You can add members two ways: one at a time, or by importing a list.
Adding members one by one
For a handful of members, use Add member. Go to Customers in the admin panel and click Add member. In the modal, find the customer and assign the membership.
If you assign a Day pass, also choose the Day the pass is for. Closed days, past days, and days the customer already holds are not allowed.
The customer needs an Alba account first, since you find them by searching their exact email address. If they don't have one yet, they'll need to create it before you can assign the membership.
Importing a list
For larger groups, go to Customers, then Import customers, where you'll find a step-by-step guide. The import can also include a value card. You can set when that card expires on the sheet; if you leave expiry blank, it defaults to 1 year after activation.
Day passes cannot be imported. Grant them with Add member or let customers buy online. See How to set up and sell day passes.
One thing to know about recurring memberships
Both methods only assign one-time (seasonal) memberships and day passes. Recurring memberships are tied to subscription and payment logic, so the customer has to purchase those themselves.