After signing in WING, you may click the vendor name at the right top, to find the VendorID starting from the letter of A or C. You can also find VendorId in the additional information page along with API keys.
ex) A000001234
vendorUserId is the login ID of that Wing account. You can find vendorUserId in Wing account information page, the ID field of your account information. Other vendorUserId of this account could be found in the account table in the same page.