Just to start, leasing a car is THE MOST expensive way to own a car.
Leasing through a dealer is very easy but may not be the most economical. There are leasing agencies (or used to be) that handle the deal as well. You decide on what you want, they’ll find the car, line up the lease and do the deal.
Insurance is another issue entirely. Best YOU contact your insurance agent and arrange insurance on the car before you finalize the lease with the deductibles and coverage required by the leasing agency. The leasing company won’t hand you the keys until they confirm insurance. You MUST maintain insurance for the term of the lease.