Hello? I'm a bit shy, so...
Hello Unnamed Dragon,
welcome to Legends of Equestria.
I hope you will enjoy the game.
If you don't feel like talking to the players at the beginning, you can talk to NPCs and see if they have some quests for you. To do this, right-click on an NPC, then you can select "Talk". Some, but not all NPCs offer quests for you. You'll often have a dialog option where you can offer them help. You can distinguish NPCs from players by their level indication. When a level is shown under their name, it's a player, if it is not, it's an NPC.
You can open your journal by clicking on the book icon in the bottom right corner. There, you can find your quests as well as your skills.
When you start the game, you will be offered an initial questline. The first quest is a tutorial, you can start it by speaking to your teacher. They are easy to find since they have an exclamation mark over their head.
The Talent Mark quest is part of the first questline. After you have completed it, you are an adult pony.
After the first questline is finished, you must walk around and talk to random ponies to get more quests.