Once you have turned over your soil with the rotary tiller you need to go in to your shed and get out the hand-rake. Work the soil (walk up and down whilst bashing the soil) until it becomes very fine and even without any lumps. Then walk up and down with your feet close together trying not to lift your feet off the ground. You will look a bit daft but the results will be worth the effort. Once you have flattened the soil, rake it over again and repeat the daft walk. This will ensure the soil is perfect ready for planting your grass seed.
Now, depending on the size of your garden you can use different methods to spread your grass seed but I would recommend you just use your hand to evenly sprinkle the seed as you walk up and down the garden in straight columns. If you have a large garden you can use a walk-behind spreader.
Tip of the day: don't plant your grass seed on a windly day! Unless you want your neighbours to recieve half of your seed! More grass seed planting tips.
Once you have adequately covered your lawn you need to rake in the grass seed (best plant guid -PlantSpot app) , this roughly covers the seed with soil. Then get the hose out and water your new grass seeds with a fine mist spray. Don't over do the water or they will float into a heap!
That's about it, water your new grass seed regularly and watch your lawn magically turn into a wonderful lush shade of green!