Tutorial for UK Taxes scheme and how it is working

I am relocated to the UK and I fell lost in all of the taxes realted stuff is there any Tutorial explaining how it is working? I have monzo saving account and I don't know if the taxes taken automatically or should I declare or submit anything I have bank account in my previous country which is the intrest already taxed, should I declare and how to declare? what is my allowed capital gain and should I declare them? If I transfered my money from my previous account to my new UK account, should be a problem?

Hi Ameeeer,
The tax you pay in the UK is dependent on a number of factors.
Tutorials can be found here: 
HMRCgovuk - YouTube
If you have a large amount of savings and earn interest on those savings you may need to pay tax on the interest earned. More information can be found here: 
Tax on savings interest: How much tax you pay
You can find details on Capital Gains Tax here: 
Capital Gains Tax
There are no tax implications for transferring savings to a UK bank account unless they generate interest or dividends.
Tax on dividends: How dividends are taxed
Thank you