I want to change battery of my Macbook Pro

Excerpted from About Mac notebook batteries:

Servicing the battery in your Mac notebook

MacBook, MacBook Air, and MacBook Pro computers with built-in batteries should only have their batteries replaced by an Apple Authorized Service Provider or Apple Retail Store. Attempting to replace a built-in battery yourself could damage your equipment, and such damage is not covered by warranty.

Consider aftermarket replacements if and only if your Mac is too old for Apple to service. In the US, OWC is a reputable vendor.

+1

Excellent advice by @ZintainUSA since the quality of Lithium-ion batteries is extremely poor. If you have an Obsolete laptop, then your best option for a third party battery is from OWC.

Try an SMC reset.

Generally the battery isn't user replaceable unless you really know what you are doing. That being said, you really shouldn't use batteries other than from Apple as you won't get the performance you are looking for and you could get some safety issues. You should take the computer to an Apple Store to a Genius Bar and have them look at the computer and they can tell you what it would cost to get the battery replaced

Is there any issues with the current battery? If no, why are you trying to replace it? If yes, what are the issues?