If you are trying to setup these records in your DO domain manager, you first need to set the nameservers to digitalocean. Currently you haven’t got this:

#1  ns03.freenom.com    ownhosting.tk   NS  IN  300 (5 min)
#2  ns02.freenom.com    ownhosting.tk   NS  IN  300 (5 min)
#3  ns01.freenom.com    ownhosting.tk   NS  IN  300 (5 min)
#4  ns04.freenom.com    ownhosting.tk   NS  IN  300 (5 min)

If you done this, wait atleast 24 hours before you are trying to get things working threw digitalocean.

Sorry for the question but how do I do this?
Could you tell me step by step how do I fix?
Thanks anyway

You have to change the nameservers at the .tk domain host. They need to point to ns1/ns2/ns3.digitalocean.com. This will tell the domain to look at DO’s nameservers which is where your records are.