Objects usually have verbs defined on them that allow players to manipulate and use them in various ways. Standard ones are:
get -- pick an object up and place it in your inventory drop -- remove an object from your inventory and place it in the room put -- take an object from your inventory and place it in a container give -- hand an object to some other player look -- see what an object looks like hide -- Hiding objects and searching for them
You can see what objects you're carrying with the 'inventory' command; see 'help inventory' for details.
Some specialized objects will have other commands. The creator of the object will usually provide some way for you to find out what the commands are. One way that works for most objects is the 'examine' command; see 'help examine' for details.