When it comes to actually buying shares the page has terms I dont understand. I take it if I want to buy or sell shares then I enter the details in the Place buy order and Place sell order tabs. But what do the bid and ask tabs below it mean especially the Fill buttons I'm not sure what they are?
The Fill buttons pre-fill out the corresponding Buy and Sell sections.
If there is a line for someone selling (ASK) 5 at 2.... and you click the Fill button, your Buy window will fill in 5 at 2 for a total of 10. At which point you can click the Place Buy Order button if you wish.
It's OK to click the Fill buttons to see what they do (they won't process an order).
Ok so
1. say if I want to buy 60 shares do I have to find a quantity of 60 then click fill and then click buy order?
2. How come the quantity to buy or sell is pre-defined?
3. How am I able to set a price I would like to sell at or do I have to choose one of the pre-defined bids then click fill?
The bids and asks are orders that are currently open, bids are orders to buy, asks are orders to sell. When you place your own order, you can choose between filling out an existing order from someone else (for example, someone is selling shares at a price you find reasonable and buy them) or create your own order in the order book (which is then added to either the bids or asks list).
If your order to buy has a price that matches or exceeds the best ask order in the order book, the order is executed immediately. If not, your order is posted among the other bid orders waiting for someone else to sell at the price you offer (and vice versa when you want to sell).
You can do all this without the fill button. All the fill button does it fill out the buy (or sell) form with the data that matches a specific order in the book, matching price and quantity. But it's rare that you want to buy the exact same quantity that the cheapest seller is selling. So the fill button doesn't have much use and I never use it and instead manually enter the price and quantity.