Hey guys looking for help for a new GM.

Hey guys looking for help for a new GM.

Hey guys looking for help for a new GM. On about my 5th session for my first campaign, can feel myself getting better a little at a time but my group has three tanks in it (Fighter, Barbarian and Paladin) i’m struggling to challenge them in combat. I know I should be trying to make it difficult for them fictionally but I’m having a hard time. Been able to challenge them in other way “traps / roleplaying challenges” but can anyone help me with making the combat more of a challenge?