Need help creating admin form to add data to custom table

I am trying to write a plugin to have a form in the admin area of wordpress that will write 10 variables (from the form) to a custom table.

I have it where the plugin creates the table if it doesn’t exist but am stuck on the function/html for writing the form data to that table.

I would also like to have a function to update a record if I choose to.

Any help? I have been struggling for hours trying to figure this out.