hi guys i need some good sites where i can pick good backgrounds for web designing so please help me here.
It depends what style you want. There are some good repeatable backgrounds here - http://theinspirationgallery.com/ or some nice textures here - http://www.cgtextures.com/ Hope this helps.
Try a gradient and tile it horizontally. Another choice for backgrounds is to take an image (glowing fractals for example) and fade it out using a soft brush in photoshop to make it go behind the main element or the top corner (assuming a centered design). You could also horizontally tile stripes. All of these, fading into a background will help reduce bandwidth. Tiling an image as a background is generally a bad idea, as it makes it look as if your site was made by a 3 year old trying to learn HTML.
That's a ridiculous comment, there are a large number of websites that use tiled backgrounds very effectively, for example - http://www.subcircle.co.uk/. I'd say using fractal gradients is far more amateur than a nicely tiled background. It is of course my own preference to use very subtle backgrounds, often with no texture or pattern at all.
You can use my textures, even for commercial projects - High resolution textures I add new ones every week.