Hi SquadLeader -
Need a little information to know what's been done so far, and what you're looking to acheive.
1) Are you a Method user, or are have you been hired as a consultant to make everything work together?
2) Regarding Method, have you already setup your account? If not, that would be a first step. Click Try it FREE at the top of this screen, and choose the QuickBooks Desktop option.
3) Regarding QB Enterprise, you just need to sync them together - not much to do other than to connect them. https://www.method.me/help/34611-get-started/253309-quickbooks-desktop
4) Regarding MailChimp, you just need to connect it to Method - no need for API work. https://www.method.me/help/35334-mailchimp/256564-mailchimp?from_search=22344326
5) Regarding Woocommerce, we have no integrations or articles on this integration. So API work would be needed here by a software developer. https://www.method.me/help/34759-api/253585-method-api?from_search=22344343
Paul