To start investing in stocks you need to open an account with an online broker. There are literally hundredsof them online. Here is a list of discount borkers that charge less than $5 per trade. 

List of cheap discount brokers.


It does not cost anything to open an account and you can start out with any balance you want.

Then,

Read investing ideas in sites like:

Investopedia

Fool


And just google for more.