how can trump pardon people that haven't been charged with a crime?how can that be?

Actually some of the predecessors that replied here may be stating archaic articles in regard to Ford and Nixon. This may not apply to Trump in terms of charges that have not been filed for said people, so he cannot preemptively file pardons for nonexistent charges until they are known.  The only way that pardons could be put in place is if the recipients exclaimed and admitted to their crimes and specified in detail what they were which could result in a pardon. This comes with risks in more ways than one. Once they admit to crimes, if they don’t admit to all of their crimes, they are susceptible to have more charges filed at a later time for additional crimes if they apply and that might result after the president has already lost his power to pardon or exited the office.

He can't. You can't pardon someone for crimes for which they've NOT been charged. It would be tantamount to pardoning someone for a fictitious crime. The pardons are null once the charges are made. 

It is because of Article II, Section 2, Clause 1 of the U.S. Constitution which reads:

"The President shall be Commander in Chief of the Army and Navy of the United States, and of the Militia of the several States, when called into the actual Service of the United States; he may require the Opinion, in writing, of the principal Officer in each of the executive Departments, upon any Subject relating to the Duties of their respective Offices, and he shall have Power to grant Reprieves and Pardons for Offenses against the United States, except in Cases of Impeachment."

Gerald Ford on September 8, 1974 granted to Richard Nixon, his predecessor, a full and unconditional pardon for any crimes that he might have committed against the United States as president.

It's a "get out of jail free" card from Trump's Monopoly set!

This administration cannot possibly get more corrupt surely? Can they?

The presidential pardon power includes preemptive pardons. 

Yeah. It makes what you are saying sound senseless. Never a source, so it never happened.