Can a flat horse start their racing career in the flat races, and if a player wants to change to hurdle or chaser races, and how do you do that, and when can you do that?

Yes, flat races start at 2 as you would expect and from 3 onwards national hunt races because available to enter if you so wish. You just toggle between flat and jumps with the button you'll see when you start the game.

Just bear in mind that a flat raced horse can`t enter bumpers or National hunt flat races only novice races or above. Starts to become a factor if you start to breed jump horses.

you see I have been racing a horse in the flat races from the age of 2 and now his 6 years of age, and now I want to change him to start racing in the jumps, but I can't find any races for him, what do I need to do to change him into a jumper, and sorry for my ignorance guys but, what is a bumper?
This side of the game is all new to me.

A bumper is a national hunt flat race, in rl often ridden by apprentices who without experience bump into each other through lack of experience hence the term bumper. Only unraced horses or horses who have been raced outside regulation ie. point to point are eligable to enter.

At 6yo and flat raced the first race you ought to be looking to enter would be a novice race. Unfortunately the game doesn`t help much, think it`s a problem with the schedules, I tend to just throw them in the deep end under these circumstances. Try hurdles a couple of times then chasing if that doesn`t work, failing that it`s time to go back to the flat or retire to stud, or the last option (not in game) glue factory.

dragon, your a legend mate well explained thank you kindly.