3Ds Max8 question: How to remove a portion of an animation

Hi, I have an animation that is 290 keys in length, or about a minute... I only want to use keys 240 to 276, deleting the rest of the keys.

It is an motion capture I downloaded from a site, an FBX file.

I am new to 3ds and just figuring out various things... but I should be able to follow instructions pretty well.

Thanks for any help

Select the animated object. All the keyframes will be displayed in the timeline.
Select the unnecessary keys and delete them.