I think there are two  -ve test cases
1)Without  giving the data in the specific  field/fields
,check for alert message
2)enter the blank space in the field/fields ,check for alert
message .

There are n number of -ve test cases.

As the First name & Last name of anyone would have only 
Alphabets so:

1. First name & Last name fields shouldn't accept numbers, 
special characters. 
2. First name & Last name fields should have validation 
like it can't accept more than 10-15 characters (Depends on 
the requirement).

As the contact number of anyone would have only numbers so:
1. The contact number field shouldn't accept alphabets, 
special characters (Except +sign for the country code).
2. The contact number field shouldn't accept more than 10 
digits.

Regards,
Imthiyaz.Shaik

Adding to Imtiyaz, few more -ve test cases which we can
include in the testing of the application are:

1. Check for the mandatory fields validation.
2. Check for number of digits we can add in the contact
number field.
3. Check for the alpha numeric characters in all the fields.

Best Regards
MTest