Welcome to the forums
First and foremost, there is no such thing as a dumb question. As an old chinese proverb goes “he who asks is a fool but for a moment, he who never asks is a fool forever” 
I think a great place for you to start is at the babypips school. They take it one step at a time and, in my opinion, do a great job of teaching the absolute newbie in a very straightforward, down to earth fashion.
In case you did already start and are still lost, the basic answer to your question is as follows:
When you are buying a pair you are in fact hioping to buy it low and sell it high. When you are short selling the pair you are hoping to sell high and buy low. I am not sure how familiar you are with the concept of short selling, though. So, if i confused then sorry.
As you know everything is quoted in pairs. So, let’s take the EUR/USD as an example. If you anticipate the pair to increase in value you are basically speculating that the EUR will appreciate vs. the dollar. If you wanted to act on that point of view, you would essentially have to BUY or go LONG the pair. This means that you are buying the EURO and selling dollars simulataneously.
If, on the other hand, you anticipate the pair to decrease in value, you are speculating that EUR will depreciate vs. the dollar. If you wanted to act on that you would have to SELL or go SHORT the pair. This means you are selling EURO and buying dollars simultaneously. Thinking in terms of the first currency as the basis of decisions helped me out.
Essentially, what you do for the first currency of the pair implies that you are automatically doing the opposite for the second currency in the pair.
If your understanding of this whole thing would be facilitated by thinkning in terms of dollars, then that is fine too. You just have to reverse your thinking if the first pair in the currency is not USD. So if you wanted to trade exclusively the EUR/USD and wanted to try and capitalize on an appreciating dollar, then you have to consider shorting (selling) the pair.