So long as the character slot with a warrior was there before paladins came out, you can still convert. Check into an inn if you are unsure, there will be a convert option there. Training is a more complex question. The very basics would include something like 2x weapon, 1x CM, 1x dodge, 1x pf, 2x armor, .5x spells, .5x Harness or perhaps 2x sword/2x board/ <1x dodge. Most people pick up alot more magic early on, but that is the bare bones version.
AIM: GS4Menos
>Here lies the formless world we´re living in
>Gravity is finally giving in
>High altitudes and still upward we go
>I was never meant to lead but to follow