Dirt inside valve cover

[cerebus]

So after leaving my truck over winter, I found a plug or sensor on my valve cover fell out. I felt inside and theres alot of dirt and grime inside the valve cover. (sorry the pic is alittle dark, its at the very left side of the valve cover)

Im pretty new at this so can I just remove the valve cover, clean all the gunk out, put a new cork gasket on and bam shes good to go?

Is there any info I should know about before doing this?

thats more like 2 or 3 questions but they are all about the same thing