In North America you must b e 18 years of age to open a brokerage account in your name
You can go to any major brokerage firms website - they offer both regular and discount business and their services are either in-house or on-line
It seems that the most popular firms for on-line investing/trading all of which provide excellent platforms and services are; Scottrade; Chas.Schwab; TDAmeritrade; Fidelity; E-Trade, Vanguard, T.Rowe Price and Thinkorswim.
The online brokers are the easiest IMO. Try looking at Scottrade, TD Ameritrade, Schwab, Fidelity, Sharebuilder, etc...
As far as age, unless it is a custodial/trust account or similar, you need to be 18 yrs old.
My online broker.
You go to the phone.
And how old must you be