A CNAME DNS record is used to point a sub-domain from your domain to another hostname. This can be useful for many reasons, lots of services require you to use a c-name record.
Name: Here you will enter what sub-domain will be used, note that c-name records DO NOT support using the main domain "uphosted.nl" in this example, for c-name records.
Value: Here you enter your target, you can find this at the provider that you are getting the record from, or it might be something of your own if you are pointing it to something you made yourself. Not that you do not need to enter a dot (.) at the end.
TTL: This is how long the record should be cached by the user's browser. If you select a higher value, users have to fetch the DNS record fewer times, this will make resolving your name faster, but updates to this DNS record will be slower.
Priority: The CNAME record does not use the priority field, you may ignore this and keep it empty.