Aubergines likes a long and warm growing season so it is best to grow them in a greenhouse or polytunnel. You could also try them on a warm sunny patio but they will crop better undercover.
Seeds are sown from late February to early April in small pots or cell trays of multi-purpose compost. The seeds need a temperature of about 18-21C (65-70F) to germinate. If you don’t have a propagator you could place them in an airing cupboard but do check them daily as they will need to be removed as soon as signs of germination appear.
After germination place the seedlings on a warm windowsill and when large enough to handle move into individual pots. Keep growing on in the warm. Plant into large pots or growing bags in a greenhouse from about April and keep watered and fed with a high potash feed. This could be a proprietary tomato feed. You may need to stake the larger plants and leave the greenhouse door open when the flowers open to allow pollinators to enter.