Well, you need to research for a backup or migration plugin and follow the prompts otherwise you can hire an experienced developer to do it for you.
you need to consider emails and other DNS records so the migration has to be planned well.
we have our WP site currently hosted with another but would like to move it to WP.
It seems there’s some confusion here, or, at the very least, a lack of clarity.
You have a WordPress-powered site already, so this is not about converting a no-WordPress site to WordPress. This is just about changing hosts.
But what is this “WP” that you want to move to?
WordPress.ORG, where you are now, is the place where the WordPress software is developed and supported. WordPress.ORG doesn’t host websites at all, so you can’t move your site here.
Perhaps you intend to move to WordPress.COM, a managed WordPress hosting provider. If so, then you’re at the wrong place. Please head over to their site, purchase a plan, and seek help from their support team if you need help: https://wordpress.com/