When you encounter an unfamiliar character, the normal way to go about understanding it is to look it up in a dictionary, etc.
There are various ways to look up characters, which I'm not going into here.
But suppose you can't find it in a dictionary, or don't have a dictionary, you can do some educated guesswork based on the make up of the character, and on what you've been familiar with. Most characters tend to contain some components that are frequently repeated in other characters, and these components can give you clues about the meaning and/or pnonunciation of new characters.
I imagine you have already found a way to look characters up, but in case you haven't, I find one of the easiest ways is to use a website such as "nciku.com" (or mdbg.net, etc) and click on the "pen icon" to input the character by using your mouse. The character will then appear with the pronunciation and you can look up the translations/definitions from there.
There are other methods such as using radical look-up, radical/visually-based IMEs (input method editors), four corner method, stroke count, etc., but they are normally a lot more complicated than the above method.