Log into your FastHosts account. (https://www.fasthosts.co.uk/)

Under the Domain menu click Manage Domains.

Select the domain name from the list that you wish to add the DNS records to.

Click into the Configure Advanced DNS link.

A list of DNS records will be shown.

Scroll Down the list and click on the blue icon "ADD TXT RECORD"

Fill out the fields with the following info:

a) Hostname: Enter the host name for the TXT record. For example, enter @ for an SPF record, or enter the value _dmarc for a DMARC record.

b) Destination TXT Value: The value you are setting as the destination of the Host.

When the information are entered, click Save.

Create a free OnDMARC account