For the 2017/18 tax year, up to £4,128 can be paid into a Junior ISA. You can divide this however you like between a stocks and shares Junior ISA and a cash Junior ISA.
Relatives can pay in money to the Junior ISA (e.g. for birthdays, Christmas or general gifts) via the registered contact – but only up to the £4,128 limit. Normally, monies can’t be withdrawn from a Junior ISA until the child reaches 18. See our Junior ISA page for more details.