New to coding and I could use a little guidance

Hi! As the title says, I am new to coding. I have read the outlines on how the macros work in this app, and by looking over other macro examples I have a better understanding as to how they are set up. Long story short, I have an animal companion with multiple attack types (bite, claws, grab, rake, and elemental damage) and I want to set up a single macro to cover a full round attack. my main question is that I haven't been able to find out how (if i can) to set the dice to highlight green for an extended critical threat range ((and vise versa for extended critical fail, i.e. for a misfire range for firearms) this is excluding inserting a clumsy statement of 'if N≥X then crit' followed by a roll). Also to nest a query(?) to roll a critical confirmation and damage given a set dice roll range, can I do this, and how would you go about it?

I would recommend you not do that.  I would get a Journal entry for the animal companion, and set up macros for each attack.  This is how I setup monsters in my 13th Age games, and how I’ve setup animal companions too. you can just use the Attributes and Abilities tab for this, ignoring the character sheet if any. Macros are easier using the Default Roll Template too. I use it for monsters exclusively.

Threat range of 19-20 would be 1d20cs>19     (the > in roll20 is actually >= mathematically) Similarly, a larger crit fail range would be 1d20cf<2   if it misfires on a 1 or a 2. Crit confirms are usually best handled in manual macros by just rolling the same attack again should it come up.  Trying to include crit rolls in every attack tends to get a little spammy.  There's no way to conditionally roll a crit confirm unless you're using a character sheet that natively supports that built-in logic (Like Pathfinder or 5e OGL)