A ten year old would have a very difficult if not impossible time careing for a horse alone. Horses require daily attention (if they are not in a boarding stable where you pay someone else to care for them) and huge ammount of money. If you have help from your parents then it is possible for you to care for one. Horses need to be fed 2-3 times daily, they need shots, vet care, training, proper handleing and disipline and exersize. Horses are not really 'pets' in the same sense as a dog or cat, people sometimes forget this then get into horses and end up in a mess (unable to care for them, or with a horse that is dangerous) You really need to learn about all aspects of horses before getting one as a 'pet'. You need to take riding lessons, and work at a stable doing barn chores before you get a horse. This will show you what goes into careing for a horse, and will teach you how to handle one safely. You can't get all the experiance you need to own a horse off the internet and books, but they can be good resources at times. It seems like you have made a good start by asking
Also a male horse is a gelding (if castrated), stallion (if left intact), or a colt (if it is young). Geldings are in genral more mellow than mares (female horses), there is no major difference in care between mares and geldings. A 10 year old should not handle a stallion under any circumstance, they can be unpredictible, strong and more aggressive.