How many signatures do I need to have a law changed or made?

Depends upon the state you're in. Most western states allow citizen "iniatives" or "propositions." If you get enough signatures (usually a percentage of the population) then it can go on the ballot for a statewide vote. If it passes, it can become law (without the legislature's approval.) Other states don't have that option at all (a good idea, in my mind. The only thing more corrupt than a legislature is a CITIZEN INITIATIVE!) So your only resort is to ask your legislators to change the law.

Here's a link to a state map showing initiative states;

http://www.iandrinstitute.org/statewide_i&r.htm

only one, it is the governors signature on the law.

You can not change a law or make a law, only your elected political people can do that.

City council makes city codes.

county board does county laws and rules

your state congress does your state law

and the federal congress does the federal laws.

a sizeable majority of legally registered voters in the city, county, or state you live in. If it is a federal law, good luck.

The number doesn't matter, its if any politicians take notice.