OK, tank size is a good place to start...what fish you intend on keeping.
What equipment have you for the tank, filter, airstones, etc?
You will need to purchase a test kit to allow you to test your water for certain things. Look into the API Master Freshwater as well as a test kit for General Hardness...avoid the test strips they give inaccurate results.
Before stocking the tank with fish, the tank will need to cycle..cycling is the process needed to create "good bacteria" to remove bad things from your water. This should ideally be done before the fish are added. You can read an article on it here
At the top of the page, you will see a link to fish profiles on the blue navigation bar..while the tank is cycling which can take 6-8 weeks, you can read up on what fish you intend on getting. Cycling a tank using fish is generally not a good idea as it can shorten the life of the fish and exposes them to certain things, Ammonia and Nitrite which in the high levels created when cycling a tank are extremely bad for their health.
Please ask as many questions as you want, our members are here to help in anyway they can, no matter how stupid you think the question is, ask it anyway. We want you to have a trouble free tank with healthy fish you can enjoy for years to come. Not to waste money on fish as they keep dying.
The information to someone who has never really kept fish before is very overwhelming but actually not all that complicated.
We look forward to helping you create a tank of your dreams (within your budget) and helping you on your journey into fishkeeping.