If you don't have any programming skills,but want to create a social networking website then go for BuddyPress.BuddyPress is a WordPress MU plugin which magically turns it into social networking website.
Though it is not designed for high end professional business(like myspace,orkut),it has most of the things you need to have your own social networking website.It is still under development and do have some bugs,which are fixed regularly by the development team.I tried it and works perfectly.Give it a try and I can assure you you will like its simplicity.

Some of the Features

Avatar Cropping and Uploading
Each member of a BuddyPress site can upload their own avatar. Avatars can be cropped to size within the browser.

Fully Customizable Profiles

BuddyPress administrators can create completely customized profile templates for members. Create any number of groups and field types.

Conversational Messaging
Private messages are threaded like a conversation making them easy to follow. Messages can be sent using the built in TinyMCE editor. Members can send messages to other friends and groups.