How to make profit from trading with Forex system marginal?

Its an easy answer .when you trade a commodity at the market .you make a profit when you buy a commodity with a price and you sell it with a higher price . right ?

But before you buy a commodity . you have to be 90 percent sure that its price will rise soon enough so you can make a profit from selling it . but . what if we expect that the price of a commodity will rise and it doesn't .. you will lose . so you have to be sure before doing any thing

now you are wondering . why would i tell you that . you clearly know . NO . i tell you that because even in bear markets . we can make a profit . you're gonna wonder how !

i will tell you how .. imagine you have a car . its price in the market now is 10000 Usd.

if car prices fall  and your car after a few day  its price will be 8000 Usd. how to make a profit of that ?!!  .. you probably think i'm crazy right now . but no . i'm gonna tell you how ... simply you will sell your car  right now before her price goes down to 8000 Usd . and then  when the price falls . buy it again ..  and when you do . you now made 2000 Usd as a profit . which means that you still have the same car and 2000 Usd .

that means you can make a profit in the bear markets with one different ..

in the Emerging market . you started the deal with buying then selling .. in the bear markets you started the deal with selling then buying .. Got it ..