If your teeth are irregular then you need to undergo orthodontic treatment (Braces) to correct them. It may take 1 to 1 and a half year or sometimes more to correct them through braces. As far as yellowness of teeth is concerned, you can go for bleaching (teeth whitening) or you can opt for veneers.

If your teeth are irregularly arranged you might have to undergo an orthodontic treatment i.e braces. If the shape of the teeth is irregular there are various procedures to correct it. If it's minor it can be corrected with a composite filling which can be done in a single sitting. If you need to go in for laminates or full crowns it might take a little longer.