Finding a Race
There are three ways to choose a race. One way is by using the Search in the racing section, another is by using the Quick Enter option (this only available if you have a Pro account). The final way is through the Tracks in the racing section. We will discuss the Tracks option here.
Once you've decided your horse is ready to race, you need to go to the Racing tab and find the Tracks button. You have already selected a region for your stable as well as a home track for your horse. On the Tracks page, the tracks readily available to you are listed in the top table (your broad region), and the tracks that are farther away are listed in the bottom table. It's always best to try to race at your horse's home track (marked with a * before the name), or at least a track in their home region, if at all possible. Horses racing outside of their region will lose much more energy in the race, due to having to travel so far.
Select a track from the list, and then select Race Card. This will give you a list of all the races currently available to enter at that track. This should tell you what meet the races are for so make sure you are entering the meet you want to enter. Races will publish for the next meet once the current meet runs. One track may still be taking entries for Meet 3 while another track is already taking entries for Meet 4. If you're unsure, check the right sidebar to see what meet the game is currently in.
The list of available races will offer a wide variety of options. There will be races on both surfaces (dirt & turf) at a variety of distances. There will also be some restrictions listed: ages, genders, even races for non-custom ('F' - for foundation; or shown as a blue circle) and custom horses ('C' for customs 25%+, and 'B' for Blueblood who must be 100% custom; may also be shown as a rainbow circle). It's always best to enter a horse in an age or gender restricted race if a suitable one is available.
Fillies usually race better against other fillies, and three year olds usually race better against other three year olds. Two year olds can only race against each other, and do not begin racing until later in the year (May), to allow them time to mature.
The race card list also shows the purse (total winnings available to horses that place) of the race and the name of the race. Within the name of the race, you can find the grade of the race for many races (such as NW2, or G3). There are several different grades available, which are explained in more detail in the section below.
All of the options available may be daunting, so take a second to look back at your horse and think of what you want to enter them in. For example, if you have a filly who has never raced before and is trained to run 10f on Dirt, you will want to look for a race for 'fillies only' at or around 10f on Dirt. (See section on Distance Types to get a better idea of what other distances a horse might like.) With those considerations, you should be able to find a race to enter your horse in. Just remember to double check age and gender restrictions, and try to pick a distance and surface you think your horse will like. If you have no clue how good the horse is, it's typically best to start out in lower levels of races, such as Allowance races, though there's also nothing wrong with testing your luck in a stakes race (your horse might surprise you!).
Take note that entering a high potential horse in a too low graded race is forbidden. You should enter 40+ potential horses in G2 and 50+ potential horses in G1. Of course peak matters and if your horse isn't peaked yet you should probably wait until they are at least 'Average' in peer comparison to not enter them too much below their grade.
Also, all races have a maximum entry limit of 1 horse per stable. If you can enter more than one horse in a race this is not supposed to happen and should be posted as a bug on the boards.