When you created the application you would have assigned a default role to it. Now that role should have the rights to insert data into the(that) table. Have a look at the app settings and see what role it uses, and then look under the "Access" tab of that role to see what it is allowed to do. If there are more CRUD ops that you want it to do, then set the Access rights accordingly.
I am just displaying an example of javascript addresbook application available in the example apps
Cheers,
M&M