Corn is wind-pollinated so should be planted in a block formation (not one long row), and the beans need to grow up the corn, so each bean seedling should be planted close to a corn plant. (In the Garden Planner it's usually recommended to avoid overlapping the colored backgrounds on adjacent plants, but in this case you can overlap them without any problems.)

The corn should be planted two or three weeks before the beans to make sure they're tall and strong enough to support the beans as they grow. It's often a good idea to plant squash or pumpkins on the outer edges of the planting to avoid the taller crops shading them too much.

Do be aware however that having so many crops close together can make harvesting the beans and corn tricky if you're using them fresh, so you may find it easier to grow only corn and beans together, to avoid accidentally trampling the squash vines while harvesting. The full three sisters layout works best when all crops are left to dry on the plants for storing.