What is your journey?
You can check the stops between your starting point and your destination here:
https://www.nationalrail.co.uk/
You can buy a ticket in advance here on the Trainline:
https://www.nationalrail.co.uk/
But the best selection of tickets is on the website of each of the train operating companies.
Are you in the UK? (although an adult who has never travelled by train in the UK is probably a unicorn!)
If not, there are special deals you can get - I think they're called a BritRail ticket, which allows you unlimited travel over a certain number of days. YOu have to purchase outside the UK - ask your travel agent.
If you book each journey, you should probably avoid peak hours - before 9:30am. After this time, you can usually buy cheaper tickets.
Most train tickets are cheaper if you do an advance purchase. The "walk up" fare is generally the most expensive. But an "Advance Purchase" ticket has restrictions: you MUST travel on that specific train, date & time.
If you buy a ticket before you travel - up to 24 hours before you travel - you can often reserve a seat.
If you choose to sit in the Quiet Zoe, do not use your mobile phone, use headphones for listening to whatever, and don't have loud conversations.
Some train operating companies are better than others - if you can outline your journey, we can probably advise you on the best route and train company.