What part are you struggling with?
The input to the ADC needs to be biased at half the supply voltage and the signal generator must be loaded with 50Ohm, to avoid reflections.
This circuit will bias the ADC at 2.5V and has an input impedance of exactly 50Ohm, at high frequencies.
What's the lowest frequency of interest? This circuit has a cut-off frequency of just over 62Hz. If you need to go lower, increase the value of C1.