How to create custom webpart to search for the list items and show in the dropdownlist, textbox controls

Hi,

I have created Lists as follows:

List 1:  name : "PersonList" with the columns " PersonName,  MobileNumber, Country"

List 2: name:   "ZipCodeList"  with the columns "Country,  ZipCode"

My task is to create a custom webpart that retrieve data from the lists(PersonList, ZipCodeList) and show in the webpart fields

My webpart fieds are as follows:

 I have created a CustomWebpart with the following fields "

Person Name:   TextBox1        Button1 [Search Button] if i click on this button, data will be shown in the other fileds w.r.t                                                   textbox1 list item

Mobie Number: TextBox2

Country:  DropDownList1    [if i select a country, that country zipcode from the "ZipCodeList" need to be shown]

ZipCode: TextBox3

Hope you understand my requirement. Please Help me with code. No url links please.. Only give code to create this webpart.