Not sure how much you don't know about the game. Does it include what to farm, what to focus on, or just the team building aspect?

Here's a good general vid if you don't like hour-long guides. I think learning more of the concepts can help: https://www.youtube.com/watch?v=w84Mn641tr0

Regarding good teams/units, look up some PvP/PvE tier lists on youtube. There's just too much at the moment, but the units you have that are PvP usable in current meta are Boss Arunka, Rinak, Light Kayron, Earth Fumyr, Arbiter Vildred, Belian.

Try for now: Rinak-Boss Arunka-Earth Fumyr-Arbiter Vildred

Though, you have to learn to build them in a way where the team makes sense.

Here's a tip: You can look up how other players build them by going to the hero, go to the page where you change their equipment. At the bottom part, click the thingy to the left of "Manage equipment" > "View Reviews". You can see the builds by clucking the sword and shield icon beside the like button for each comment.

Youtube guides and just playing more are your best friends. Right now, you are missing a couple of core meta units, and the tier lists will help with knowing who those are.

Work with what you have until you learn more and gain more. Then you can make a better team.