Sure.
There is a list of broker reviews here on this forum:
http://www.trade2win.com/boards/broker-reviews/
It depends what markets you wish to trade.
In general what you do is you go to the online site. You fill in details under "open an account" and it will ask you things such as age, job, savings, location etc. (Age/location for law) - (Job/savings for collateral so that they can get their money back if you go under your account). They can claim it back by law.
The accounts are usually opened within minutes. They should then send you some documentation through post and some will ring up to check everything is fine and you are who you say you are. - You don't have to fund your account till its open.
I assume you already know what they are but heres an overview:
Forex is currencies.
Commodities is energy/food/metal etc
Equities is shares.
Bonds is debt.
Each has different swings in price ranges on a fast scale.
It also depends whether you want to own the underlying asset or spreadbet. (I can't recomend any as i think it is a against forum rules - it could also be conflict of interest as i could be anyone giving you any link/scam).
Spreadbetting are basically "Book-makers" for lack of a better term and should give you access to a range of markets together for example forex/bonds/commdities/equities - some more-so than others. They make the money primary through the spread and if you lose (or so i believe).
Spreadbetting allows you to bet that prices are going down as well as up - however you have to pay any dividend payments from your account if you are betting down when the dividend has agreed to be paid.
However the link above that links to a different section of this forum should help.