Trouble getting measurments of my circuit
You have done an transient analysis, do an AC sweep ( I don't know what version of multisim you have but here are instructions for the latest version)

An AC sweep will allow you to get an amplitude vs frequency plot. 

If you still want to find dB, you can do this for a transient plot, you need to know the amplitude of voltage in and voltage out, then calculate dB

\$   dB = 20*\log_{10}\frac{Vout}{Vin}\$