thinkradically

Hey everyone, I'm trying to print my first design and nothing is going as planned. I should first state that all the preloaded designs print just fine, so I feel like the hardware is set up appropriately. When I try to print something I designed and saved as gcode file it doesn't stick to the printing bed. The printing tip has PLA coming out of it, but it just doesn't stay on the bed. If i'm right in thinking it's not a hardware issue (due to pre-loaded designs working), what am I doing wrong with the design / within Cura???? Thanks pc