nth-child and pseudo elements

[PoW8]

 Hello, I wanted the “content” for each menu to be different. How do I properly use a child selector to make the first menu and second menu have different images?

 Thanks in advance.

[PoW8]

I’m sorry. I’m not quite sure how to type it and proper spacing. This is the code I’m using…

.grid .footer-block__heading::after {
content: "+";
position: absolute;
right: 0;
top: 50%;
transform: translateY(-50%);
width: 20px;
text-align: center;
}
.grid .footer-block__heading:not(.block-collapsed)::after {
content: "-";
}

I copied this and changed the content but was unsure on the proper placement of the child selector. Would you mind adding it to this code? 

[PoW8]

If you can walk me through the exact steps of what I should be typing and where, that would be greatly appreciated. I know a little about coding from videos and articles but can’t actually code, only edit existing code for now. 

I want the menus to have different ::after “content” to be distinct buttons. Unsure how to specify that element, which from what I understand they are pseudo elements.