how can i fix my cracking screen

See this for costs:

iPad Repair - Official Apple Support

As babowa points out, the usual action is that, on receipt of your broken iPad, they ship you a refurb of the same model and specs. This shows what a refurb means:

https://www.apple.com/shop/browse/overlay/refurbished/ipad

I did the service with an iPad battery repair last January and had the replacement iPad in six days including two weekend days. Very pleased. Note that means you must backup your iPad and remove all information from your ipad before sending.

Either start a repair ticket using the get support link in the upper right corner of this page or go to any authorized repair center. Depending on the extent of the damage, Apple may decide not to repair but offer a replacement; price will vary greatly depending on your warranty status.