Dont know how to tighten my toilet seat...i have the studio 2 piece from american standard

How to Change Toilet Seat This Old House

Put your hand around the back of the seat and you will feel the nuts. Tighten them by simply turning them.

Check the chain the goes between the handle and the flapper.
It should not be taught. If it is it will not permit the flapper to seat
properly and water will leak out. Adjust the chain length so the flapper is seated and there is just a little slack in the chain.

They all work pretty much the same. Feel around the top rim of the bowl near where the tank meets the bowl you should find one bolt underneath on either side of the toilet seat. Tighten the nut under there to tighten the seat.

Your toilet is still offered by the manufacturer:

http://www.americanstandard-us.com/toilets/williamsburg-one-piece-elongated-toilet/

Available replacement toilet seats from American Standard can be seen and ordered here:

http://www.americanstandard-us.com/repair-parts/toilet-seats/

You might consider finding you nearest dealer or choose another on-line retailer:

http://www.americanstandard-us.com/dealerLocator.aspx

Before ordering suggest you confirm with American Standard Customer Service the appropriate replacement seat for your model.

http://www.americanstandard-us.com/customerservice/onlineStoreSupport.aspx

You can order from the American Standard website:

http://www.americanstandard-us.com/repair-parts/toilet-seats/?so=&r=10&p=1

You can also search for a retailer/distributor near you who will probably carry replacement parts. See here:

http://www.americanstandard-us.com/dealerLocator.aspx

American Standard Town Square Series Toilet - Two-piece -$300
http://www.homecenter.com/ProductDetails.asp?SID=213163

Toto CST754SFN 1.6GPF ADA Compliant Two-Piece Elongated Toilet (Less Seat) -$330-520
http://www.build.com/toto-cst754sfn-1-6gpf-ada-compliant-two-piece-elongated-toilet-less-seat/p144049?source=spg_144049&aid

KOHLER K-3654-0 Persuade Two-Piece Elongated Toilet with Dual Flush Technology, Less Seat in White -$340
http://www.overstockdeals.com/KOHLER_K_3654_0_p/k-3654-0.htm?utm_medium=shoppingengine&utm_source=pricegrabber&Click=1964

probably the flapper valve is not seating correctly over the outlet. you can fix it by reaching in and twisting the valve one way or the other till it seats properly and the leak will stop.

Replace the flappers, and clean around the flapper seat.

Make sure the water level is 1/2 " below the large vertical tube by either bending the float rod down or adjust the skinny silver rod on a Fluidmaster unit.

http://www.americanstandard-us.com/customerservice/Care/TroubleTreeDetail.aspx?TopicID=2&Depth=2&AnswerText=Two-Piece%20Gravity-Fed&QuestionID=107&ModelNumber=&ProductType=2-Piece%20Gravity&ProductName=

Follow the link above, it will probably answer any questions you may have for your particular toilet. They are all different and without the model number, it's hard from my point of view to understand what you may need. Hope this helps you!