Writing a book?

I am thinking about writing a book. I am completely in the dark on this topic. I mean I have a good idea for this book and I think it would do well as I haven't seen any books written on what I am thinking about but how do I go about it?

I know first I have to write a rough draft...that may take me years alone. Then I know I have to send it to publishers and try to get them to notice it. That is the part that has me concerned. How do I get noticed being a first-time author?  Will anyone take what I have to say seriously?

I wish I had a big audience that read my blogs so y'all could give me advice on this. Should I even tackle this? I mean I love to blog. Is that even a step in the right direction?  Please send me ideas or places to look!

Signed,
Budding Author.