Welcome to the wonderful world of biking!
Welcome imdawn!
Like MightyMitre said, there's a ton of great tips and advice on this forum! And if you have a specific question post it and the responses/replies will come forth! :p One piece of advice I would like to share is, increase your saddle time slowly! Starting with 12 miles was great then work from there. Let your body (and butt) get used to sitting in the saddle. Let your legs and lungs get stronger with each successive ride. Riding clothes are important too. Believe me those tight padded lycra shorts are just the thing for cycling! :D
Again welcome and keep us posted on how you are doing.
Sue