So this is my first time playing a warlock and I’m only level 1. Whenever I click cast on the dnd beyond app on one of my spells both get greyed out and the little pact button turns red… is that normal? Why does using one of my spells effect both ?

Level 1 Warlocks only have 1 spell slot.  So as soon as you cast a leveled spell you cannot cast another until you take a short or long rest.

You'll get a second spell slot when you hit level 2! 

You should read the section on Pact Magic on the warlock page, it goes over how warlock spell slots differ from spell slots for other classes.

Oh! That makes much more sense now! Thanks everyone!