It's impossible to look at a beers ingredient list and derive an exact recipe from it. You have to go through a process of trial and error, using any information you can get from the manufacturer combined with experience or intuition.
However, the good news is that you probably won't have to do that yourself, because its highly likely someone else already has. Copying a commercial style is usually referred to as cloning, and for many beer styles you can simply google "commercial beer style + clone". Depending on how popular that beer style is, there might be a large number of recipes out there, or there might be a few dedicated people who have done all of the trial and error for you.
For example, a search for the Samuel Adams beer you linked to produces a few good leads and a fair amount of discussion. Sometimes its better to get discussions rather than straight recipes because it will help you to understand what is needed and why certain ingredients and processes are favoured over others.
Homebrewing forums usually have whole subforums dedicated to cloning, and the various homebrew software packages usually have ways of sharing recipes online to make it easy for others to find (BeerSmith for example.
Now, some recipes may use an all extract approach, some may use all-grain, and some may use a combination. So it's probably best to find a recipe that suits your experience and equipment. If you are just learning about homebrewing and have no idea how all-grain differs from all-extract, then you should read John Palmer's 'How to Brew' which is online. It covers everything a new brewer needs and then some.
I'd probably advise brewing from basic recipes before you get into cloning. Because once you have a fair amount of experience under your belt from that, you'll understand all the nitty gritty details like when to add which hops and how that will affect the beer etc.