I understand that you are asking about the basics of data base design, right ?
Well, this question can not be answered in one or two sentences, the required design of your data base fully depends on what information it will hold, and on what you want to do with this information.
If you wanted, for example, to create a data base with all the phone numbers and addresses of people in Greece, you would need two tables.
Table1 would hold the Name|Surname|StreetName|HouseNumber|PostCode|PhoneNumber ,
Table2 would hold PostCode|CityName
If you "connected" both tables using the PostCode field you could display all information from each record from table1 PLUS the CityName from table2.
If you add a field SHOW in table1, which can hold only YES or NO, you could design a statement that shows only the records marked SHOW = YES, or those marked NO. You would do this to avoid being presented with all addresses which you do not wish to see (because marked NO means "not my friend any more" for example).
As you see, this is a very complex issue.
Maybe you could specify your question to what exactly you want to achieve to bring in the most helpful answers .
Regards,
Bernd