Squealing Belt

[supremefaulk]

I realise there are a few topics mentioning this, but I have already searched, and none of them offer advice on how you can tighten the belt to stop it slipping and squealing.
Any help out there?
Thanks in advance

 

[edde]

Whats engine?

 

[supremefaulk]

Its a 1.2 engine, its a Mk1 clio if that makes any difference