Treating upwards as postive:
F(net) = F(centripetal) = Tension - Weight = 0
Tension - Weight = 0
therefore, Tension = Weight
Remember to refer to tension rather than F(N) as it is more specific. Also with the net force equation, make sure that there is a negative before the Fg/ Weight as it is acting in the opposite direction to the tension force.
What I also want to point out is that you can treat the equation with the variables as vectors or scalars. I prefer scalars (you account for direction with negative signs). Your net force equation is fine if you keep vectors in mind, but since you specified up as positive then treating them as scalars is the way to go. This also means that when referring to the forces in the equations, you are only concerned with their magnitudes when solving. If you do this correctly for all force equations, you will only get positive values for magnitudes of forces when solving as you have accounted for the direction (whether positive or negative) already in the equation.
If you would like me to show you both methods (vector and scalar) and how the solutions present themselves when you solve, Iet me know and I'll prepare something tomorrow.