Theory:

Nouns can be classified in two ways, COUNTABLE and NOT COUNTABLE or UNCOUNTABLE.
A countable noun can be counted, like PEOPLE.
A not countable noun cannot be counted, like MUSIC.

When used with countable nouns, SOME means an undefined plural number, and is used with ARE.
For example:
There ARE SOME French people at the party.(We don't know how many.)

When used with uncountable nouns, SOME means an undefined amount, and is used with IS.
For example:
There IS SOME milk in the fridge.(We don't know how much.)

SOME and ANY mean the same thing.
SOME is used for POSITIVE sentences and ANY is used for NEGATIVE sentences and QUESTIONS.
For example:
There are SOME French people at the party. (positive)
There aren't ANY French people at the party. (negative)
Are there ANY French people at the party? (question)

SOMEBODY, ANYBODY, NOBODY, EVERYBODY

SOMEBODY means a a single unknown person.
For example:
There is SOMEBODY in the kitchen. (one undefined person)

The rules for SOME and ANY apply to SOMEBODY, SOMEWHERE, SOMETHING, SOMETIME.
For example:
There is SOMEBODY in the kitchen. (positive)
There isn't ANYBODY in the kitchen. (negative)
Is there ANYBODY in the kitchen? (question)

A negative sentence using ANYBODY can be changed into a positive sentence using NOBODY.
For example:
There isn't ANYBODY in the kitchen.
There is NOBODY in the kitchen.

EVERYBODY means all the individual people.
It can be used for all kinds of sentences.
for example:
EVERYBODY is in the garden.(positive)
EVERYBODY is not here. (negative)
Is EVERYBODY here? (question)

The same logic applies to SOMETHING, ANYTHING, NOTHING and EVERYTHING.
For example:
There is SOMETHING in my hand.(positive)
There isn't ANYTHING in my hand.(negative)
There is NOTHING in my hand.(positive)
EVERYTHING is in my pocket.(positive)