How do I add parameters/arguments to commands?

Hello! How do the parameters work when adding commands?

I want to create a command that is written like this; "/damage" and containing the following parameters; "<entity> <amount>", this would look like this; "/damage <entity> <amount>", but I don't know how to add parameters.

PD: the parameters would work as follows ...

"<entity>": (Examples: "@a", "@e", "@e [type=minecraft: zombie]", etc ...)
"<amount>": (Amount of damage you want to do to the selected entity)