I’m 6’5" and about 270. I have a large frame. I just got a gym membership a week ago and have been going pretty consistently so far. I need a good routine though. My goals for now are weight loss, core strength and definition. I’ll worry about muscle gain later.

Make your gym routine to about 3 times a week. That way its not too intense and its just about achievable
Don’t do much weights for now….so you won’t gain much muscle and you will lose calories.

Now for your definition…by which i assume you mean weight loss and weight gain in the right areas….this is all about naturally losing the fat content first and then building up your frame. Once you start going to the gym..whatever you do..the fats will always go from the heavy areas…and after 2 months or so..when you are ready to gain muscle ..you can work the right areas!

If you need diet plan this site may help you

http://beam.to/revealweightlossfact