Can someone please advise about Keywords

Dear Warriors,

I am relatively new to internet marketing, but know about how to do keyword research, set up a WP blog etc and have an understanding about link building, article marketing etc to help with SEO. However, I am a little confused about something and I don't know if I am just being a bit thick and apologies in advance if I am.

My question/s are:

If I research a keyword or keyword phrase lets say for example "how to draw a map" using Google's keyword tool and it returns a global monthly search of 68,000,000 and a local search or 5,000,000 and the competition is low. am I correct in assuming that that is a good keyword phrase to use as long as I can get the keywords in the domain name?

Secondly when using the keyword tool, you can click on the phrase and it will open in up a new window in google and take you to that search term or phrase. However, it then says it has returned About 1,340,000,000 results (0.12 seconds).

I think I am getting confused by the keyword tool saying the competition is low because if I understand it correctly this is what it amounts to:

68,000,000 is the number of people around the world who have searched for "how to draw a map" in that month.

1,340,000,000 is the number of keywords that have satisfied the criteria "how to draw a map" from pages that exist on the web.

If the above is correct, why does the key word tool say that the competition is low and if that's the case is it a good keyword phrase to use?

Have I got it totally wrong? Sorry if I have confused you.

Thanks for responding.

Skeeloj