if you want to buy a stock you can buy it on the bid or buy it on the ask?

if you sell a stock you can sell it on the bid or sell it on the ask?

when you play breakouts where do you need to buy the stock? on the bid price or the ask price?

when you sell the stock, where do you need to sell the stock, on the bid or the ask price?

when your shortsell, where do you need to sell, on the bid or the ask price? and when your cover where do you need to buy? on the bid or on the ask price?

i am new when it comes to trading stocks, and i am hoping to get some answers on this subject, thanks.