Standard English has single negation, and a double negative means a positive. A double negative is where there are two negatives in the construction; however many people use the phrase only to mean a "double-negative *error*".

The OED says "**double negative** n. Grammar a syntactic construction containing two negative elements, esp. where only one is now expected in Standard English; either of the negative elements in such a construction."

* **I ate** simple positive statement
* **I didn't eat** simple negative statement
* **I didn't eat anything** negative statement
* **I didn't eat nothing** double negative which means "I ate something".  This is a rare construction which which emphasises that it isn't nothing.  "I didn't eat nothing, but it was very small."
* **I didn't not eat** double negative, which means "I ate".  This is a rare construction which emphasises that that it happened.  "I didn't not eat, but it was so small it wasn't really a meal.

Your example
>I do **not** want you to go **no**where.

This is a double negative, which in standard English is rare and would only be used as emphasis: "I do not want you to go _nowhere_, I want you to go _somewhere_."

The usual sentences would be:

* **I do not want you to go** or **I do not want you to go anywhere** Which means "I want you to stay"
* **I want you to go nowhere** which means "I want you to stay here" (but is somewhat awkward.)

Additionally, there are **many varieties of non-standard English** which have "negative agreement", and you will hear "I didn't eat nothing" where standard English has "I didn't eat anything".  Unless you are living in an area where the locals speak like this (many parts of South London, for example), you should learn the standard variety, but be aware that many native speakers do not speak Standard English.