To make basic vanilla ice cream, you need to make vanilla custard and then freeze it. You can add flavours to your basic custard and by adding them before freezing. For mixed berry ice cream I get a bag of frozen mixed berries (strawberry, blackberry, raspberry etc.), and I heat them up in a pan with sugar until I get a "mush", then force that through a sieve to get sweet fruit puree. Whenever you're making ice cream you need everything to be too sweet before freezing, it will taste less sweet when frozen.
You can try to make it without an ice cream maker, once you're custard is cool, put it in the freezer and then take it out repeatedly and give it a couple of minutes with an electric whisk (or maybe process in a food processor), then put in freezer again, and repeat this several times. But I've never managed to get smooth ice cream this way, the problem is that water crystals form and make it taste grainy. The ice cream maker freezes the custard quite quickly while churning it all the time so the crystals don't form. Another way is to use dry ice or liquid nitrogen (hazardous!) but I don't think many people have access to these "ingredients".
For the custard I use these ingredients:
3 egg yolks
300 ml (1/2 pint) double cream
300 ml (1/2 pint) milk
1 vanilla pod
You can substitute vanilla essence for the pod, but it will be less 'fancy'
You can experiment flavouring the milk in different ways for different flavours, and go wild with garnishes for interesting tastes.