Dale at this point , you should already be able to make a satisfactory pizza using commercial yeast (ADY/IDY). If you haven't gotten to that point yet, then I would hold off on learning how to make pizza with a starter. This is considered my most to be advance pizza making. The reason being is that there can be several pitfalls to using starters that can drastically affect your outcome for the worse.
Having said that, there is nothing wrong with experimenting and trying new things. It's just unsuccessful bakes can be very discouraging especially when you are starting out and it's nice to have a sure pie to fall back on just in case.
So if and when you are ready, one method is as follows. You can use anywhere from less than 1% to more than 50% of the flour weight in starter depending on how slow or fast you want to ferment your dough. If you are using more than 10% or so in starter, you should recalculate your new hydration rate. Starters, particularly in large amounts can raise your hydration rate by 3-4% or more. To do this, just add half the weight of the starter to the flour side and half to the water side of the recipe (assuming your starter was fed with 50% of each making it a 100% hydrated starter) and recalculate the new hydration ratio.
A simple method of using a starter is to dissolve the active starter in the formula water, then dissolve your salt (and sugar), oil, then flour, and commence mixing.
Just as a loose guide, and at a room temperature of 75f, 1% active starter can fully ferment a moderately hydrated dough in roughly 20hrs, while 10% will take about 12-14hrs, and 20% will take roughly 6-8 hours.
You have to experiment a little and take good notes. When switching over from a commercial yeast to a starter, it's a good idea to stick with a forumula that you are familiar with so you can see how the starter affects the dough and final product.