Hello
@Ianwigan , welcome to the forums

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If you wish to join online races, it's very simple:
1/ select Drive
2/ select Online
3/ pick a server
4/ pick a car
5/ press join
And you will be racing in no time

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X/
BONUS: if you see track name (or car name) in red color, it means you don't have that content - it's either from a DLC Pack you don't own, or a modded track/car.