What is the systamatic investment plan and how can i invest that?

Systematic Investment plan is similar to Recurring Deposit Schemes of the Post Office and Banks. They are offered by the Mutual Funds. You regularly invest a fixed sum every month in the mutual fund scheme. The fund allocates units based on the NAV applicable on the date of investment.
You will be called upon to deposit post dated cheques or give an ECS mandate.
In this method, when the NAV is high you get lesser number of units and when the NAV is low you get more units. Hence the average cost of the units will be low. It cultivates the habit of regular saving.
Usually, since the fund flow is assured, the mutual fund houses offer incentives such as waiver of entry load, or lowering minimum investment amount.
Contact any of the investment advisors or mutual funds. You will be asked to fill in an application form and provide some identication proof. You may either hand over 6 or 12 post dated cheques or sign ECS mandate to the effect that a fixed sum can be collected from your Bank Account.

Almost every good Mutual Fund company has a "systematic investment plan". It allows you to automatically draw funds from your checking account into your mutual fund.

Some good no-load fund companies are;
Vanguard, T. Rowe Price, Fidelity and many more.

There are also "systematic investment plans" known as "DRIPS" (Dividend Reinvestment Plans) for individual stocks (GE, J&J, Motorola, HSBC, Barclay's etc).

You can also do the same with savings accounts;
GMACBank, ING, HSBC etc. Most on-line savings accounts pay over 5% and are FDIC insured (in USA).