Basically people have covered how to roast a chicken already, but I just wanted to add that you don't need the lemon unless you want it to be a little lemon flavored. My personal variation on the chicken-seasoning theme is to rub the inside and outside with a good amount of butter, salt and pepper and then to roast in the oven at about 350ish until 1) the juices run clear when you poke it and 2) the leg seems almost ready to just come off when you pull on it a bit.
After you take the chicken out of the oven, you should also prop it on a plate breast-down and let it sit covered for 10 or 15 minutes in order to let the juices "reabsorb" into the chicken so it's moister. At least that's what all the youtube videos told me and what I have done with good results

You can also chop veggies like potatoes, carrots, brussels sprouts, onions etc. into largeish chunks and scatter them over the bottom of your roasting pan, drizzle with olive oil, then put the chicken on top of them and roast them altogether. That way the veggies create air circulation space under the chicken and also get seasoned in the delicious chicken drippings.