How GSEA determines the gene sets with nominal p-value < 5%. ?

Question

[Amr]

How GSEA determines the gene sets with nominal p-value < 5%. ?

After getting the report of GSEA, how GSEA calculates the gene sets which have specific p-value for example <1% or 5 % ?

Thanks

[Arup Ghosh]

https://www.pnas.org/doi/10.1073/pnas.0506580102