First check with your local nursery, they are most likely to have a variety that will thrive in your zone. As you have cold winters, you will need to winterize the fig tree if planted in the ground or your will have to carry it inside during the cold months.

If your nursery doesn't have any, you can try a big box (HD, Lowes, etc) store.

Last, you can order online. There are a number of reputable online nurseries you can order from.

What they sell at the nursery is what was available for them to buy. Few if any do their own propagation or choose appropriate varieties, just getting one that is properly labeled is good luck! I hear all the time from people in my area "my tree makes figs but they never ripen".

What you want is an Etna type, it would help to know your region as far as local sources.

You are in zone 6/7 so that means any fig you get will need to be protected for the winter. So you need to be prepared to bring the fig tree into an unheated garage or covered sufficiently in ground. You need to do some research for what methods works best for you for this.

For zone 6/7 early ripening common type figs are best.

The sure winners are the so called Chicago type dark figs (Mount Etna Types) or for light figs Fico Bianco/Italian Honey/Lattarola are great choices.

Good Luck