My basic rule of thumb is -- if someone is asking this question, they're not really qualified to remove the sideplate. No offense, but I've seen too many buggered up screws, scratched frames & sideplates in my time.
If you want to learn the internals, pick up The S&W Revolver - A shop manual By Jerry Kuhnhausen (VIP Press) before you begin. Worth three times it's price.
You can replace the screws yourself. If you want to properly work on a firearm -- be it replacing screws, mounting a scope or a complete refitting -- I suggest looking for a quality hollowground screwdriver set such as the Chapman kit. Then use the proper size driver bit for each screw.
Sir William has a good point. Clean the screw holes (sounds dirty doesn't it?) with a little spray degreaser. Do the same to the screws. Then, before assembly, put a drop of oil on thumb & finger, smear it around, dab off excess, then roll the screw between oily fingers to protect it without gobbing oil on it. Run screw down to contact point and wait about 2 minutes for any excess oil to seep up. Then tighten with 2 fingers about 1/8th turn. The tiny, thin film will ease removal later. Check screws after firing 10-20 rounds for tightness.
To remove old oil & crud from a wheelgun, use a commercial spray cleaner/degreaser. Use outdoors only with plenty of ventilation. See my article elsewhere on "How to clean a revolver" for lubrication.
It may be well worth about $15 or so to have a gunsmith show you how to properly remove the sideplate and clean & lube the internals. And hopefully the gunsmith will be happy that you're taking the time to learn how to properly maintain your gun from him.