First of all, you have 4 horses (2 females and 2 males), however their enclosure isn’t big enough. They don’t feel unhappy in it, so the Park Inspector won’t mention it, but they won’t breed either, and you need a lot of profit from selling horses. So, that’s something to deal with as soon as possible. You can’t enlarge the horses’ current paddock, because there is not enough place around it. Simply build a relatively big wooden fence enclosure somewhere else with at least one small herbivore house, along some animal keepers, and put the four horses there. Hopefully, you’ll see some notices soon that your female horses got pregnant. Their gestation period is 11 months, so you'll have to wait for that. Nevertheless, it’s possible they’ll give birth to 2 or 3 foals instead the average 1, which should mean a lot of profit for you (also note again, baby animals are worth more money than adult ones).
While waiting for the foals to get born, build some flat rides (especially thrill rides) to have an adequate monthly profit, and build new enclosures for animals. Note that some of the animals are unavailable in this scenario so you will soon run out of animals that are fine with just the cheap wooden fence enclosure (the zebra and the Bactrian camel). Because of that, you’ll have to build chain fence enclosures (or electric ones, but try to refrain from that, as those are very expensive) for more animals. I bought a pair of red kangaroos and some giraffes as well as some of the aforementioned zebras and Bactrian camels, but any animals should be fine. Always price the viewing galleries. You can ask for 150%-200% of the initial $1.00 (if the guests complain about it being too expensive, lower the price a little until they find it all right). Also, build thrill rides near the enclosures to attract the guests there. After a few enclosures, you will notice that you start to run out of useful space on the “ground floor”. There are several useful flat plateaus with plenty of places for enclosures and rides, you just need to connect them to the park. Don’t do elevated paths, because the cost of the pylons will eat up all your money. Rather, try to build underground tunnels underneath the mountains leading up to the plateaus. You could build transportation rides, too, such as a Chairlift, but it costs really a lot, so it’s maybe not the best idea.
With all the enclosures, animals, priced viewing galleries, rides and shops you should have at this point, it should fulfill both the park value and the monthly viewing gallery income objectives up to tycoon. Hence, all you have to do is waiting for the horses to give birth and then sell the foals. If the horses give birth to 2-3 foals each, the profit you get from selling them should cover the selling animals objective up to tycoon, and you won apprentice, entrepreneur and tycoon.