Hi
and welcome!!
If you're at the very beginning, I think the best place to start is by logging your food. That's the very first thing my personal trainer had me do when I started. Once you keep track of
everything you eat for a week or so, then you can get a realistic sense of what you need to cut out or what needs to be replaced by a healthier food choice.
I am a firm believer in taking "baby steps." It's much easier to change lots of little things over time than it is to suddenly change EVERYTHING all at once -- that will leave you feeling deprived, which may lead you to giving up before you've even begun!
I started out by doing only 2 things the very first week. I cut down on Coke (I was drinking 4 - 5 cans a day) and I replaced the sugar in my tea with Splenda. Every week I changed a few more things. I added weight training and cardio and slowly adapted to my new lifestyle.
Do you have a specific plan in mind? Any thoughts on what kind of exercise you'll be doing?
Again, welcome! You'll love it here!