Not a noob question at all.
The formula for Doppler shift is relatively simple, see e.g. the Wikipedia article on Doppler effect. We can assume stationary observer:
f = f_0 × (c / (c + v_sat))
Here f_0 is the nominal frequency and v_sat is the velocity of the satellite with respect to the observer (not the orbital velocity). In predict and gpredict this velocity is called "range rate" and you can see that typical values are between 5-10 km/s, depending on the orbit shape and altitude.
If we take 10 km/s we have:
f = f_0 × (299792 km/s / (299792 km/s + 10 km/s)) = 0.999967 × f_0
So, for example, at 436 MHz the Doppler shift will be within ± 20 kHz