Adding Keywords

I have a website up and running (www.montemuse.com using 2011 Theme). This was a major learning effort for me as I am a complete novice. I have an idea what keywords are for, but no idea how to begin adding them to my pages, headers, titles, metadata (whatever that is) etc.

I can’t find any info on existing forums that are basic enough to explain the first steps.

1. Is there some way within WordPress to add keywords to the appropriate places directly, or does one use a plug-in? If so, can you recommend one that a novice who knows nothing would understand?