If you are new to this you may like to try the following as a combination for a small community tank
One male Siamese Fighting fish. Males have big elaborate fins (Do not be tempted to get two as they will fight each other and cause harm, especially in a small tank
Eight Neon or Glowlight Tetras, these are shoaling fish and make a beautiful colourful addition to the tank
Three Albino, Peppered or Pygmy catfish. They are beautiful and very playful, completely made/suited for an aquarium tank
Once your tank is well set up, you could think about adding three Black Tetras. These are bigger than Neons and are aggressive but only to other Black Tetras (other Tetras will be fine), but they don't hurt each other, just let them know who the boss is)
HTH