as i am a newbie.. i know nothing about trading... what should i do to start trading and multiply my btc.. guys please help me
If you onlly have small amount of money, don't trade it since it's not worth it. It's better if you would just gamble it so you can multiply it easiy if you're luck then use it to do trading.
Suggesting people to gamble instead of trade is not wise advice. We can't easily win on gambling sites, and mostly we are only losing on gambling sites. Rather than gamble, would be better if you invested those small amount with some ICO/ cheap altcoin (not shitcoins) and keep re-invested until you have decent amount.
Gambling and trading has something in common, that is the uncertainty to win. Even experienced gambler or trader on that matter can't possibly predict if they are going to win.
But what makes a trader apart from a gambler is the ability of the former to control losses. With that being said, you (OP) have the full discretion whether to trade or gamble.
And oh, to answer you question, you can start trading with even a small amount but you must couple it with a lot of patience and determination.