Let's start with the abilitys!

Q : Ekko's Q is very important mainly in the laning phase, use this to poke your opponent, but be careful because this ability has a high mana-cost! Also use this to slows your opponent, and remember you get a Passive stack! In teamfights use this ability to poke before going in Or to escape (this slows).

W : W is also important in the laning phase, but also in the late game/teamfights. In the lane use this to trick your opponent to run into this, then use your E (Phase Dive) to get in range and stun your opponent.

E : E is a core ability for ekko's mobility. Use this ability in lane to engage or disengage. In late game use this to either pick up their carryes or generally low players on their team, or to disengage a teamfight. Remember you can jump over some of the wall on the rift but not all! Try this on a custom game.

Lets start with some laning combos.
Start with setting down you W, atfer some seconds jump in with your E, triggering the stun/shield, then use your Q for a free Q, try to hit the Q when it comes back too, for more damage, and at this point you have triggered your Passive, either continue on the fight, or run out without taking any damage.