Have a read of setFieldValue and Location Query
https://www.wix.com/corvid/reference/wix-dataset.Dataset.html#setFieldValue
https://www.wix.com/corvid/reference/wix-location.html#query
Read other previous posts too.
https://www.wix.com/corvid/forum/community-discussion/parse-url-to-get-a-parameter
https://www.wix.com/corvid/forum/community-discussion/wixlocation-to-get-and-use-http-query