How to know a real broker

I started using this broker called fresh forex and I got their bonus and it says I should trade up to a certain amount when I get the amount I should deposit so I can withdraw the profit made with the bonus.
Please has anyone heard of fresh forex

The best thing is to read carefully the Terms of Use (or Terms and Conditions) on the website of the broker. In that document they describe how they proceed your trades. Sometimes it is enough to make a decision to look for another broker.
Another point of attention is regulation. It is better to work with the broker registered in serious jurisdiction like US or UK.

These are two main criteia, and they are much more important, than commissons, spreads or anything else. Using such approach while choosing the broker you can reduce non-market risks.

More to this is transparency, what you see should be what you get at the end of the day. And another important factor is their withdrawal mechanisms, you should be able to withdraw your profits with ease.