If your tickets say Sold Out and you know this not to be the case, it's likely because you have your tickets set to Assigned Seating without any seating inventory.  If you aren't ready to create the seat inventory quite yet, it's best to start out with General Admission.

Go to Components > Tickets > Setup tab

Change the Ticket Type to General Admission.

You can change this to Assigned Seating later when you are ready to add your seat inventory.

See Assigned Seating in the Tickets Help area for more detailed instructions.