Tomatoes are relatively easy to grow from seed. All we need to do is put two or three seeds into a small pot of good light compost. The seeds need to be covered with a light covering of compost. Gently water the pots initially and keep the compost moist. Keep the pots in a light warm place, around 21 c.
If you have a warm window put them near there or possibly use one of the plastic propogators, even one of the heated ones would be great for this.
In the UK as in most countries when you start growing from seed depends on which part of the country you are in. In the warm more southern areas seeds can be sown fro late February. In the colder more northern areas where there is less light due to cloud cover, mid March is probably a better bet.
Again following the above the tomatoe plants can be grown through until October / early November.