Probably go buy a loading manual first - or two or three. Nosler, Speer, Hornady are on my desk and get used the most. Front 30% to 50% of the manuals walk you through step by step how to reload - what to do, what not to do.
And you are going to discover right away that no two sets of pressure tested data are going to be the same - they are reporting what they got, with their rifle, with the bullets, brass, powder and primers that they list. No real good reason to expect your rifle to be exactly the same as theirs. All bets are off, as a beginner, if you use any different components than they did - different brand or lot of powder, brass, bullets, primers.
Very common, apparently, for ammo makers to "customize" the powder that they use in their commercial loads. In a lot of cases (most?) you will not be able to buy the exact powder blend or lot that they put into their factory made ammo, so you will be using a "commercially available" powder to produce a similar product - but will not be using "the factory powder", in most cases.
I suspect that you will be into relatively slow burning powders - DO NOT go lower amount of powder than a book's Start load, and, until you have more loading experience and have learned to assess pressure, DO NOT go past the book's MAX load. Can get "squirrelly" fast - trying to help an acquaintance with a 7mm STW and H1000 powder - 6 different loading manuals - some have Max loads that are less than other book's Start loads. We went on-line to Nosler website - exact same Start and Max loads listed there for 160 and 175 grain bullets - obviously a "clerical" error, putting 160 grain data into 175 grain chart - but unfortunately that was the one and only source that he started with.
Makes hand loading "fun"...