How do I fix the tables in the MBR.

After prepping for a clean install and doing same,I now have 2G Partition on a 40 G drive.How do I adjust the tables in the MBR to match the info in FDISK? This problem is in my home comp. running 98SE on a P3 550 system.I have fdisk and formatted the drive twice and still get the wrong info.Any help will be greatly appreciated.Thanks Cliffjos54@cs.com