Any tips on how to get more friends irl and online?

So my names Vio and im 15yrs from Stockholm, Sweden 
and I always have hade difficulty to make friends or be social in larger groups of people>:(
and that I hate abt myself and how much of a coward I am. So I just was wondering if there are any people who lives in Stockholm and if so.. Hej hej läget lol. or someone who just lives in Sweden thats occasionally visits Stockholm from time to time.