Try to google: transimpedance amplifier photodiode
You should see circuit schematics how to properly amplify a photodiode signal.
For the sunlight problem, are you familiar with high pass filter? Or AC coupling? Sunlight is basically a constant light or slowly changing light signal, right? So sunlight -> electrical domain should also be slowly changing, which can be considered as DC signal. Just AC-couple or high pass the output of your amplifier output. Then you should be fine. Be aware of amplifier saturation(output voltage hitting the maximum output voltage) because sunlight can be very intense when shined directly to photodiode.