the diffrence between funder and co-founder

i don’t know the difference between founder and co-founder.

please tell me
thanks alot

Founder - an individual person who founds something.
Co-founder - one of a group of people who join together to found something. Could also be indicated as 'one of the founders.

Thank you so much Mr/Mrs Beeesneees .

I know a lot of English words(like:all words in 504 essential words and so on )
But unfortunately ,I can’t use these words effectively.
I don’t know what i should to do. I can’t write or speak simple sentences easily.i have to think much for this and not sure about it.
I am a little confuse and disappointed of learning English.

Mehran B[/b]