As I have become a bit more comfortable with my asrtoberry setup and using kstars/ekos I would like to start taking additional frames to hopefully help with my stacking.  I was already taking dark frames, but I guess I want to check if I am doing all this right.

For dark frames I cover my scope and take 20 or so frames at the same conditions as the subs  I took.  I then drop all of those frames into DSS with my light subs and stack.
Flats confuse me still.  I covered my telescope with some white cloth and tried to get even lighting (have a light on the way) and used the calibration wizard or whatever in ekos.  I just selected Flats > dust cap with light > and then number of frames I wanted.
I am lost on the difference between bias and darks.

So my questions are what are bias frames and how do you take them? For flats do I need to do any post processing or does it work just like darks and I throw them all into dss for it to make a master flat file (do I need to do any histogram editing or anything first)?  I want to figure this out because the biggest issue I have with my pictures now is vignetting and then gradient circle stemming out from the center ( I assume this may be light pollution).
 

John,
Bias is part of every image you take.
So, it is part of a light, dark and flat image.
Whenever you take a dark away from a light or flat image you are also removing the bias because it is part of the dark.
You can however create a master bias image by taking the shortest exposure your camera will take in the dark tto create a bias frame, and stack multiple for a master bias. You can then include it in your processing workflow.
Although some people do this, it is not necessary unless you are taking darks with a different exposure length to your original images.
Paul

Thanks. As far as flats go is there anything special I need to do? Do I just select flats in the drop down list click calibrate and do I pick a number on the right hand side or do I let it do auto? Then after that do I need to do anything special with those flats or just put them in dss to stack and make a master?

John,

I have tried the auto setting but found that it would change exposure times during a flats run so I now always determine the setting I want for each filter and program the sequences in as I would capturing images. After the flats I do a series of darks for each of the flats.
I then create a master flat for each filter using ASTAP and process my images.
Paul