You can use the price of the shares on your statement, to work out the value of the shares at the time they were gifted to you. This can then be used to work out if there is a capital gain, by
deducting the Allowable costs (including purchase price) from the Disposal proceeds. If thre is no capital gains tax to pay, then there is nothing to report to HMRC. There is a calculator at:
Tax when you sell shares
If there is a capital gains tax liability, you can report and pay the capital gains at:
Report and pay your Capital Gains Tax
before 31 December or in a self assessment tax return after that date.