In root position you will use fingers 1-3-5 in the right hand and 5-3-1 in the left hand for all keys in both major and minor.
A major triad in root (basic) position has the notes spaced a third
apart. The bottom third is a major third (2 whole steps apart) and the
top third is a minor third (1 1/2 whole steps apart).
The lowest note, the "root", gives the name to the triad/chord. For example; this is a C major triad or chord:
You can play a triad starting from any key on the piano of course. Just count 2 whole steps (or 4 half steps) from your starting note (counting as 1) up to the next, and then 1 1/2 whole steps (or 3 half steps) up to the last note.