To insert a record, you will need to HTTP POST the following information to http://servername/apiput.aspx 

username=(user) 
password=(password) 
path=(path) 
actionid=insert 
json=(json) 

The (user) entry should be a valid username, and (password) should be a base-64 encoded version of the password. 

Note: The password is encoded to stop casual snooping of the login information, but it is not particularly secure. If possible use HTTPS to access the server. 

The (path) variable is the XPath to the location in the database where you wish to insert the record.

Finally, the (json) entry will be the base64-encoded JSON of the record you wish to insert.

For example:

username=test 
password=(base64 encoded password) 
path=/Reports[Name="My Reports"]/History 
actionID = insert 
json= (base-64-encoded version of this data) { ReportID: "46135", Title: "This Is My Report" }