Use the IRAC method to write the case brief.

Facts: You need some of the history of the cross in the facts. When was it made and by whom? Who paid for it and took care of it. How did it eventually end up in govt hands and paid for with taxpayer dollars? Then The American Humanist Association, AHA for short, sued the National Capital Park Commission for using government funds to repair and maintain a 40- foot tall cross in a memorial park in Bladensburg, Maryland. The cost of the repairs came out to the tune of approximately $117,000 dollars, with $100,000 more being set aside for future maintenance. makes sense. Now who brought the suit and why? Wasnt it something about being offended to have to drive by and see it every day and not wanting tax dollars paying for it? Then that is enough. The rest is better placed in the reasoning.
If there is more than one issue, brief must look like this:
Issue
Holding
Reasoning
Issue
Holding
Reasoning
Issue
Holding
Reasoning
I would try to use the smallest amount of issues, like just one unless Alito specifically had more than one issue.

I would use this link to get help reading the case. You are missing too much from Alitos opinion, and might see more in the other opinions with a little help. You certainly can and should Google for other detailed help with the case. Take the help you get, go back and read the case, and see if you can see what the one summarizing the case sees in the opinions.
Reasoning: (Alito) ¦..   Only the first name as that is the writer. Only discuss another justice in that other justices opinion. Focus on Alitos writing here. Lemon Test, Establishment Clause, Alitos new proposed historical test, if any philosophy is guiding his opinion: origionalist/non origionalist, activist/restrainer, etc., and any thing else you see with his opinion.
Concurring: (Breyer) ¦.
Concurring: (  )
Concurring etc
Summarize each concurring opinion this way. What of Alitos opinion does the justice agree with and what not.
Dissenting: (Ginsberg) ¦¦ What disagree with? How would do things differently? Etc. Philosophy etc.
Your opinion: What do you think of that new proposed historical test for old monuments? I cannot tell if you agree somethings meaning can change over time. I assume the answer is no. Good compromise? Other things from Alitos opinion agree or disagree with and why. Other opinions?