You can grow an avocado as a pot plant from the stone in the middle of the shop-bought fruit. Just put it over a jar of water with one end in the water. When it's sprouted, transfer it to a pot. But it is a vigorous plant and will soon outgrow that pot. And it won't give you tasty fruit.
If you want to grow avocados and if you have the space - they are large trees - get a grafted tree from a garden centre. Hass is the most common variety and is the one in supermarkets now.
A smaller tree, better for home gardens, is called Reed. The avocados ripen throughout the year, except for a short time in early winter. They are rich in monosaturated oils and vitamins A and B, and low in sugar and cholesterol, so the tree is a great investment in healthy eating. You can plant a tree now. They like all-day sun, and some protection from wind and frost. They don't like soil that is too wet. Your first fruit should occur three to four years after planting, so be patient. The wait is worth it: a 7-year-old grafted tree can bear more than 200 fruit annually.
A perfect summer lunch is a mashed avocado with lemon juice and a little olive oil, mounded on toast. Easy and delicious.