I am very new to points/miles/upgrades, so those questions will probably sound dumb, but hopefully you guys can help me, i booked a flight from LAX to ATH with Lufthansa through frankfurt (on expedia) and i want to know if i can use points to upgrade my flights to business class

i have about 6k points with United Airlines, 60k with AMEX and about to get 75k with capital one venture x card, can i combine the points or somehow use the points for the upgrade?