Analysis

A whole bunch of things make the price go up and down. Exceeding expectations. Not meeting expectations. Mergers that seem like a good idea. Mergers that seem like a bad idea. Anything. Nothing. Somebody thinks the current price is cheap buys from somebody who thinks the current price is expensive.

Analysing, or trying to guess if the market will go up or down, falls into two broad categories - fundamentals and technicals.

Fundamental analysis is when you make trading decisions based on your knowledge of a company (or country).

Technical analysis is when you make trading decisions based on your interpretation of the movement of that company's share price (of of the currency).

While fundamental analysis and technical analysis can be mutually exclusive, they don't have to be. You might have decided through fundamental analysis that a company's share price is severely overvalued, but you can then use technical analysis to decide when to actually open the trade.
 

Announcements

When significant announcements take place, it often causes a currency's price to spike in one direction or the other, and sometimes both.

It's not really a good time to be in an open trade. (Unless you're specifically trying to "trade the announcement").

So, we find out when they are going to happen by going to the Forex Factory Calendar. Major announcements have the red icon next to them.